High Performance Auto Layout

Transcription

1 #WWDC18 High Performance Auto Layout Ken Ferry, ios System Experience Kasia Wawer, ios Keyboards 2018 Apple Inc. All rights reserved. Redistribution or public display not permitted without written permission from Apple.

2 Auto Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

3 Auto Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

4 ios 12 improvements Internals and intuition Building efficient layouts

5 ios 12 improvements Internals and intuition Building efficient layouts

6 Performance Improvements in ios 12 You get it for free

7 Performance Improvements in ios 12 You get it for free

8 Performance Improvements in ios 12 Shorter bars are better Long Row Deep Hierarchy Collection View Moving Tree Hierarchy Removal

9 ios 12 improvements Internals and intuition Building efficient layouts

10 ios 12 improvements Internals and intuition Building efficient layouts

11 Simple Layout text1 text2

12 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

13 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

14 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

15 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

16 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

17 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

18 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

19 The Render Loop What is updateconstraints? Update Constraints Layout Display

20 The Render Loop What is updateconstraints? Update Constraints Layout Display

21 The Render Loop What is updateconstraints? Update Constraints Layout Display

22 The Render Loop What is updateconstraints? Update Constraints Layout Display

23 The Render Loop What is updateconstraints? Update Constraints Layout Display updateconstraints() layoutsubviews() draw(_:) setneedsupdateconstraints() setneedslayout() setneedsdisplay() updateconstraintsifneeded() layoutifneeded()

24 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline,] metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

25 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline,] metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

26 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func layoutsubviews() { text1.removefromsuperview() text1 = nil text1 = UILabel(frame: CGRect(x: 20, y: 20, width: 300, height: 30)) self.addsubview(text1) text2.removefromsuperview() text2 = nil text2 = UILabel(frame: CGRect(x: 340, y: 20, width: 300, height: 30)) self.addsubview(text2) super.layoutsubviews() }

27 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func layoutsubviews() { text1.removefromsuperview() text1 = nil text1 = UILabel(frame: CGRect(x: 20, y: 20, width: 300, height: 30)) self.addsubview(text1) text2.removefromsuperview() text2 = nil text2 = UILabel(frame: CGRect(x: 340, y: 20, width: 300, height: 30)) self.addsubview(text2) super.layoutsubviews() }

28 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

29 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints+=nslayoutconstraint.constraints(withvisualformat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints+=nslayoutconstraint.constraints(withvisualformat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

30 // This is ok! Doesn t do anything unless self.myconstraints has been nil d out override func updateconstraints() { if self.myconstraints == nil { var constraints = [NSLayoutConstraint]() let views = ["text1":text1, "text2":text2] constraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) constraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(constraints) self.myconstraints = constraints } super.updateconstraints() }

31 // This is ok! Doesn t do anything unless self.myconstraints has been nil d out override func updateconstraints() { if self.myconstraints == nil { var constraints = [NSLayoutConstraint]() let views = ["text1":text1, "text2":text2] constraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) constraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(constraints) self.myconstraints = constraints } super.updateconstraints() }

32 The Render Loop Do you really need to be part of it? Useful: Avoiding wasted work Dangerous: Runs a lot

33 Interface Builder

34 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

35 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

36 Activating a Constraint Internal structure View

37 Activating a Constraint Internal structure Window View

38 Activating a Constraint Internal structure Window View Engine

39 Activating a Constraint Internal structure Window View Engine Constraint

40 Activating a Constraint Internal structure Window View Equation Engine Constraint

41 Activating a Constraint Internal structure Window View Engine Constraint Equation

42 Activating a Constraint Internal structure Window View Engine Variable Constraint Equation

43 Variables Unknowns layout must calculate miny minx height width

44 Activating a Constraint text1 text2

45 Activating a Constraint text2.minx = text1.minx + text1.width + 20 text1.minx = 20 text1 text2 text1.width = 100 text2.width = 100

46 Activating a Constraint Internal structure Window View Engine Variable Constraint Equation

47 Engine text1.minx = 8 - c1.marker text1.width = c2.marker text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

48 Engine text1.minx = 8 text1.minx = 8 - c1.marker text1.width = c2.marker text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

49 Engine text1.minx = 8 text1.minx text1.width = 8 = c1.marker text1.width = c2.marker text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

50 Engine text1.minx = 8 text1.minx text1.width = 8 = c1.marker text1.width text2.minx = = 130 text1.minx - c2.marker + text1.width + 20 text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

51 Engine text1.minx = 8 text1.minx text1.width = 8 = c1.marker text1.width text2.minx = = 130 text1.minx - c2.marker + text1.width text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

52 Engine text1.minx = 8 text1.minx text1.width = 8 = c1.marker text1.width text2.minx = = c2.marker text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

53 Engine text1.minx = 8 text1.minx text1.width = 8 = c1.marker text1.width text2.minx = = c2.marker text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

54 Engine text1.minx = 8 text1.minx text1.width = 8 = c1.marker text1.width text2.minx = = c2.marker text2.minx text2.width = 138 = c1.marker - c2.marker + c3.marker text2.width = c4.marker

55 Activating a Constraint Triggering the layout pass View Engine

56 Activating a Constraint Triggering the layout pass View Value for variable changed! Engine

57 Activating a Constraint Triggering the layout pass View Superview setneedslayout() Value for variable changed! Engine

58 The Render Loop Update Constraints Layout Display

59 The Render Loop Update Constraints Layout Display

60 UIView.layoutSubviews() Copying data from engine to subview View Engine

61 UIView.layoutSubviews() Copying data from engine to subview View Engine, what are the values for the variables? Engine

62 UIView.layoutSubviews() Copying data from engine to subview View Engine, what are the values for the variables? Subview setbounds(), subview setcenter() Engine

63 UIView.layoutSubviews() Copying data from engine to subview View Engine, what are the values for the variables? Subview setbounds(), subview setcenter() Engine

64 UIView.layoutSubviews() Copying data from engine to subview View Engine, what are the values for the variables? Done! Subview setbounds(), subview setcenter() Engine

65 // Don t do this! Removes and re-adds constraints potentially at 120 frames per second override func updateconstraints() { NSLayoutConstraint.deactivate(myConstraints) myconstraints.removeall() let views = ["text1":text1, "text2":text2] myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "H: -[text1]-[text2]", options: [.alignallfirstbaseline], metrics: nil, views: views) myconstraints += NSLayoutConstraint.constraints(withVisualFormat: "V: -[text1]- ", options: [], metrics: nil, views: views) NSLayoutConstraint.activate(myConstraints) super.updateconstraints() }

66 Churning

67 Churning

68 Local Versus Global Layout You don t pay for what you don t use text1 text2 text3 text4

69 Local Versus Global Layout You don t pay for what you don t use text1 text2 text3 text4

70 Local Versus Global Layout You don t pay for what you don t use text1 text2 text3 text4

71 Unrelated Views Don t Interact text1.minx = 8 - c1.marker text1.width = c2.marker text2.minx = c1.marker - c2.marker + c3.marker text2.width = c4.marker

72 Unrelated Views Don t Interact text1.minx = 8 text1.width = 100 text2.minx = 20 + text1.minx + text1.width text1.minx = 8 - c1.marker text1.width text3.minx = 130 = 8 - c2.marker text2.minx text3.width = 138 = c1.marker - c2.marker + c3.marker text2.width text4.minx = 100 = c4.marker text3.minx + text3.width

73 Unrelated Views Don t Interact text1.minx = 8 text1.width = 100 text2.minx = 128 text1.minx = 8 - c1.marker text1.width text3.minx = 130 = 8 - c2.marker text2.minx text3.width = 138 = c1.marker - c2.marker + c3.marker text2.width text4.minx = 100 = c4.marker

74 Unrelated Views Don t Interact text1.minx = 8 text1.width = 100 text2.minx = 128 text2.width = 100 text1.minx = 8 - c1.marker text1.width text3.minx = 130 = 8 - c2.marker text2.minx text3.width = 138 = c1.marker - c2.marker + c3.marker text2.width text4.minx = 100 = c4.marker text4.width = 100

75 Performance Scales Linearly When No Interaction How much work would it take by hand?

76 Performance Scales Linearly When No Interaction How much work would it take by hand?

77 Performance Scales Linearly When No Interaction How much work would it take by hand?

78 Performance Scales Linearly When No Interaction How much work would it take by hand?

79 Performance Scales Linearly When No Interaction How much work would it take by hand?

80 Performance Scales Linearly When No Interaction How much work would it take by hand?

81 The engine is a layout cache and dependency tracker.

82 Model The Problem Naturally Don t avoid using constraints Long text might be here Or maybe it s down here and this field is bigger?

83 Model The Problem Naturally Don t wedge two layouts into one set of constraints Long text might be here Or maybe it s down here and this field is bigger?

84 Model The Problem Naturally Don t wedge two layouts into one set of constraints Long text Long might text be might here be here Extra! Or maybe it s down here and this field is bigger?

85 Model The Problem Naturally Don t wedge two layouts into one set of constraints Long text might be here Long text might be here Extra! Or maybe it s down here and this field is bigger? Or maybe it s down here and this field is bigger?

86 Is That Everything? Costs of other auto layout features Inequality NSLayoutConstraint set constant Priority

87 Is That Everything? Costs of other auto layout features Inequality NSLayoutConstraint set constant Priority

88 Error Minimization Constraints with non-required priority View Engine

89 Error Minimization Constraints with non-required priority View Engine, what are the values for the variables? Engine

90 Error Minimization Constraints with non-required priority View Engine, what are the values for the variables? Engine Minimize error

91 Error Minimization Constraints with non-required priority View Engine, what are the values for the variables? Subview setbounds() Engine Minimize error

92 Performance Intuition Don t churn Basic algebra Engine is a layout cache and tracker You pay for what you use

93 ios 12 improvements Internals and intuition Building efficient layouts

94 ios 12 improvements Internals and intuition Building efficient layouts

95 #WWDC18 Building Efficient Layouts Kasia Wawer, ios Keyboards 2018 Apple Inc. All rights reserved. Redistribution or public display not permitted without written permission from Apple.

96 Constraint Churn New solution, same layout Extra work happens with no visible result Enough churn can affect performance

97 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

98 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

99 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

100 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

101 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

102 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

103 Building a Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

104

105

106 Finding the Problem

107 Finding the Problem

108 Finding the Problem

109 Finding the Problem

110 Finding the Problem

111 Finding the Problem

112 Finding the Problem

113 Finding the Problem

114 Finding the Problem SemiSocialMedia.AvatarView UILabel Quite a hike UILabel May 25, 2018 UILabel Hiked up the steps to the

115 Finding the Problem SemiSocialMedia.AvatarView UILabel Quite a hike UILabel May 25, 2018 UILabel Hiked up the steps to the AvatarView Title label Date label Log entry label

116 Finding the Problem AvatarView Title label Date label Log entry label

117 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

118 Building a More Performant Layout Title Lorem June 6th, 2018 Author

119 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

120 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

121 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

122 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.

123 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

124 Building a More Performant Layout Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

125 Building a More Performant Layout imageconstraints = Title June 6th, 2018 Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

126 Building a More Performant Layout imageconstraints = Title June 6th, 2018 [,,, ] Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.

127 Building a More Performant Layout imageconstraints = Title June 6th, 2018 [,,, ] Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. noimageconstraints = [ ]

128 Building a More Performant Layout imageconstraints = Title June 6th, 2018 [,,, ] Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. noimageconstraints = [ ]

129 Building a More Performant Layout imageconstraints = Title June 6th, 2018 [,,, ] Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. noimageconstraints = [ ]

130 Building a More Performant Layout imageconstraints = Title June 6th, 2018 [,,, ] Author Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. noimageconstraints = [ ]

131 Before

132 Before

133 After

134 After

135 After (ios 11)

136 After (ios 12)

137 After (ios 12)

138 Constraint Churn Avoid removing all constraints Add static constraints once Only change the constraints that need changing Hide views instead of removing them

139 Intrinsic Content Size Not all views need it Views with non view content: UIImageView returns its image size UILabel returns its text size UIView uses it to make constraints

140 Overriding Optionally override for text measurement Return size if known without text measurement Use UIView.noIntrinsicMetric and constraints

141 Overriding Optionally override for text measurement Return size if known without text measurement Use UIView.noIntrinsicMetric and constraints override var intrinsiccontentsize: CGSize { } return CGSize(width: UIView.noIntrinsicMetric, height: UIView.noIntrinsicMetric)

142 System Layout Size Fitting Size systemlayoutsizefitting(_ targetsize:) Used when combining with frames

143 Getting Size from the Engine Engine is created Constraints are added Layout is solved Author Size of the top view is returned Engine is discarded

144 Getting Size from the Engine Engine is created Constraints are added Layout is solved Author Size of the top view is returned Engine is discarded

145 Getting Size from the Engine Engine is created Constraints are added Layout is solved Size of the top view is returned {50,120} Author Engine is discarded

146 Getting Size from the Engine Engine is created Constraints are added Layout is solved Author {50,120} Size of the top view is returned Engine is discarded

147 Unsatisfiable Constraints There is no solution for the specified constraints Logging will help you to debug Can mask other issues See related session for debugging tips Mysteries of Auto Layout, Part 2 WWDC 2015

148 Ready, Set, Go! Think before you update constraints Tune as needed Enjoy your faster layouts

149 More Information UIKit and Layout Lab Technology Lab 2 Thursday 11:00AM

150