Cocoa Touch Best Practices

Transcription

1 App Frameworks #WWDC15 Cocoa Touch Best Practices Session 231 Luke Hiesterman UIKit Engineer 2015 Apple Inc. All rights reserved. Redistribution or public display not permitted without written permission from Apple.

2 Agenda

3 Agenda App Lifecycle

4 Agenda App Lifecycle Views and View Controllers

5 Agenda App Lifecycle Views and View Controllers Auto Layout

6 Agenda App Lifecycle Views and View Controllers Auto Layout Table and Collection Views

7 Goals

8 Goals Performance

9 Goals Performance User Experience

10 Goals Performance User Experience Future Proofing

11 App Lifecycle Best practices begin here

12 Launch Quickly

13 Launch Quickly Return quickly from applicationdidfinishlaunching

14 Launch Quickly Return quickly from applicationdidfinishlaunching Defer long running work

15 Launch Quickly Return quickly from applicationdidfinishlaunching Defer long running work App killed if too much time passes

16 Beyond App Launch Being responsive to every input

17 Beyond App Launch Being responsive to every input Not just about asynchrony

18 Beyond App Launch Being responsive to every input Not just about asynchrony Move long running work to background queues

19 Beyond App Launch Being responsive to every input func application(application: UIApplication, didfinishlaunchingwithoptions launchoptions: [NSObject: AnyObject]?) -> Bool { globaldatastructure = MyCoolDataStructure() globaldatastructure.fetchdatafromdatabase() } return true

20 Beyond App Launch Being responsive to every input func application(application: UIApplication, didfinishlaunchingwithoptions launchoptions: [NSObject: AnyObject]?) -> Bool { globaldatastructure = MyCoolDataStructure() globaldatastructure.fetchdatafromdatabase() } return true

21 Beyond App Launch Being responsive to every input func application(application: UIApplication, didfinishlaunchingwithoptions launchoptions: [NSObject: AnyObject]?) -> Bool { globaldatastructure = MyCoolDataStructure() dispatch_async(dispatch_get_main_queue()) { // defer work until later globaldatastructure.fetchdatafromdatabase() } } return true

22 Beyond App Launch Being responsive to every input func application(application: UIApplication, didfinishlaunchingwithoptions launchoptions: [NSObject: AnyObject]?) -> Bool { globaldatastructure = MyCoolDataStructure() let globalqueue = dispatch_get_global_queue(dispatch_queue_priority_default, 0) dispatch_async(globalqueue) { // defer work until later globaldatastructure.fetchdatafromdatabase() } } return true

23 Launch Quickly Again

24 Launch Quickly Again System Memory

25 Launch Quickly Again Kernel + OS Processes System Memory

26 Launch Quickly Again Foreground App Kernel + OS Processes System Memory

27 Launch Quickly Again Background App Background App Background App Background App Foreground App Kernel + OS Processes System Memory

28 Launch Quickly Again Background App Background App Background App Background App First to Die Foreground App Kernel + OS Processes System Memory

29 Launch Quickly Again Background App Background App Background App Foreground App Background App First to Die Foreground App Kernel + OS Processes System Memory

30 Launch Quickly Again Background App Background App Background App Foreground App Foreground App Kernel + OS Processes System Memory

31 Leverage Frameworks

32 Leverage Frameworks Reduce maintenance burden

33 Leverage Frameworks Reduce maintenance burden Get improvements for free

34 Leverage Frameworks Reduce maintenance burden Get improvements for free Focus time on what makes your app special

35 Leverage Frameworks Properly manage version change

36 Leverage Frameworks Properly manage version change Target two most recent major releases

37 Leverage Frameworks Properly manage version change Target two most recent major releases Include version fallbacks

38 Leverage Frameworks Properly manage version change Target two most recent major releases Include version fallbacks e.g., if systemversion == 9.0

39 Leverage Frameworks Properly manage version change Target two most recent major releases Include version fallbacks e.g., if systemversion == 9.0 e.g., if systemversion >= 9.0

40 Leverage Frameworks Properly manage version change Target two most recent major releases Include version fallbacks e.g., if systemversion == 9.0 e.g., if systemversion >= 9.0 e.g., if #available (ios 9.0, *) {}

41 Leverage Frameworks Properly manage version change Target two most recent major releases Include version fallbacks e.g., if systemversion == 9.0 e.g., if systemversion >= 9.0 e.g., if #available (ios 9.0, *) {} Have an else clause

42 Views and View Controllers A best practice for every screen

43 Layout on Modern Devices

44 Layout on Modern Devices

45 Layout to Proportions

46 Layout to Proportions Avoid hard-coded layout values

47 Layout to Proportions Avoid hard-coded layout values A UILabel to contain some content

48 Layout to Proportions 30 Pts 260 Pts Avoid hard-coded layout values A UILabel to contain some content

49 Layout to Proportions 30 Pts 260 Pts Avoid hard-coded layout values Either or both dimensions may scale A UILabel to contain some content

50 Layout to Proportions Avoid hard-coded layout values Either or both dimensions may scale A UILabel to contain some content Centered

51 Size Classes

52 Size Classes Some size thresholds trigger major change

53 Size Classes Some size thresholds trigger major change iphone 4S

54 Size Classes Some size thresholds trigger major change iphone 5

55 Size Classes Some size thresholds trigger major change iphone 6

56 Size Classes Some size thresholds trigger major change iphone 6 Plus

57 Size Classes Some size thresholds trigger major change ipad

58 Size Classes Some size thresholds trigger major change iphone 6 Plus

59 Size Classes Some size thresholds trigger major change Packaged in UITraitCollection iphone 6 Plus

60 Properties, Not Tags!

61 Properties, Not Tags! Avoid settag: and viewwithtag:

62 Properties, Not Tags! Avoid settag: and viewwithtag: Possible collisions with other code

63 Properties, Not Tags! Avoid settag: and viewwithtag: Possible collisions with other code No compiler warnings

64 Properties, Not Tags! Avoid settag: and viewwithtag: Possible collisions with other code No compiler warnings No runtime errors

65 Properties, Not Tags! Avoid settag: and viewwithtag: Possible collisions with other code No compiler warnings No runtime errors Instance variables and properties provide better alternative

66 Properties, Not Tags! let ImageViewTag = 1000 class ViewController: UIViewController { override func viewdidload() { super.viewdidload() } } let imageview = UIView(frame: CGRect(x: 0, y: 0, width: 50, height: 50)) imageview.tag = ImageViewTag view.addsubview(imageview)

67 Properties, Not Tags! let ImageViewTag = 1000 class ViewController: UIViewController { override func viewdidload() { super.viewdidload() } } let imageview = UIView(frame: CGRect(x: 0, y: 0, width: 50, height: 50)) imageview.tag = ImageViewTag view.addsubview(imageview)

68 Properties, Not Tags! class ViewController: UIViewController { var imageview : UIImageView override func viewdidload() { super.viewdidload() } } imageview = UIView(frame: CGRect(x: 0, y: 0, width: 50, height: 50)) view.addsubview(imageview)

69 Make Timing Deterministic

70 Make Timing Deterministic Leverage UIViewControllerTransitionCoordinator

71 Make Timing Deterministic Leverage UIViewControllerTransitionCoordinator Animate alongside a transition

72 Make Timing Deterministic Leverage UIViewControllerTransitionCoordinator Animate alongside a transition Get accurate completion timing

73 Make Timing Deterministic Leverage UIViewControllerTransitionCoordinator Animate alongside a transition Get accurate completion timing Support interactive and cancelable animations

74 Auto Layout Layout ninjas unite

75 Modify Constraints Efficiently

76 Modify Constraints Efficiently Identify constraints that get changed, added, or removed

77 Modify Constraints Efficiently Identify constraints that get changed, added, or removed Unchanged constraints are optimized

78 Modify Constraints Efficiently Identify constraints that get changed, added, or removed Unchanged constraints are optimized Avoid removing all constraints

79 Modify Constraints Efficiently Identify constraints that get changed, added, or removed Unchanged constraints are optimized Avoid removing all constraints Use explicit constraint references

80 Modify Constraints Efficiently override func updateviewconstraints() { super.updateviewconstraints() } view.removeconstraints(view.constraints()) view.addconstraints(self.generateconstraints())

81 Modify Constraints Efficiently override func updateviewconstraints() { super.updateviewconstraints() } view.removeconstraints(view.constraints()) view.addconstraints(self.generateconstraints())

82 Modify Constraints Efficiently override func updateviewconstraints() { super.updateviewconstraints() } view.removeconstraint(imageviewhorizontalconstraint) imageviewhorizontalconstraint = self.generateimageviewhorizontalconstraint() view.addconstraint(imageviewhorizontalconstraint)

83 Modify Constraints Efficiently override func updateviewconstraints() { super.updateviewconstraints() } view.removeconstraint(imageviewhorizontalconstraint) imageviewhorizontalconstraint = self.generateimageviewhorizontalconstraint() view.addconstraint(imageviewhorizontalconstraint)

84 Modify Constraints Efficiently override func updateviewconstraints() { super.updateviewconstraints() } view.removeconstraint(imageviewhorizontalconstraint) imageviewhorizontalconstraint = self.generateimageviewhorizontalconstraint() view.addconstraint(imageviewhorizontalconstraint)

85 Modify Constraints Efficiently override func updateviewconstraints() { super.updateviewconstraints() } view.removeconstraint(imageviewhorizontalconstraint) imageviewhorizontalconstraint = self.generateimageviewhorizontalconstraint() view.addconstraint(imageviewhorizontalconstraint)

86 Constraint Specificity De-duplicating constraints

87 Constraint Specificity De-duplicating constraints Duplicates are implied by existing constraints

88 Constraint Specificity De-duplicating constraints Duplicates are implied by existing constraints Duplicates cause excess work in layout engine

89 Constraint Specificity De-duplicating constraints Top Bottom

90 Constraint Specificity De-duplicating constraints Top Bottom "V:[Top]-[Bottom]- " + NSLayoutFormatAlignAllLeft

91 Constraint Specificity De-duplicating constraints Top Bottom "V:[Top]-[Bottom]- " + NSLayoutFormatAlignAllLeft "H: -[Top]- "

92 Constraint Specificity De-duplicating constraints Top Bottom "V:[Top]-[Bottom]- " + NSLayoutFormatAlignAllLeft "H: -[Top]- " "H: -[Bottom]- "

93 Constraint Specificity Create flexible constraints

94 Constraint Specificity Create flexible constraints Avoid hard-coded values

95 Constraint Specificity Create flexible constraints Avoid hard-coded values A UILabel to contain some content

96 Constraint Specificity Create flexible constraints Avoid hard-coded values 30 Pts 260 Pts A UILabel to contain some content

97 Constraint Specificity Create flexible constraints Avoid hard-coded values 30 Pts 260 Pts A UILabel to contain some content V:-30-[Label(==260)]

98 Constraint Specificity Create flexible constraints Avoid hard-coded values 30 Pts 260 Pts Describe constraints using bounds A UILabel to contain some content

99 Constraint Specificity Create flexible constraints Avoid hard-coded values 30 Pts 260 Pts Describe constraints using bounds A UILabel to contain some content V:[Label(<=superview - 60)] NSLayoutFormatAlignAllCenterX

100 Constraint Specificity Fully specify constraints

101 Constraint Specificity Fully specify constraints Underspecification generates ambiguity

102 Constraint Specificity Fully specify constraints Underspecification generates ambiguity

103 Constraint Specificity Fully specify constraints Underspecification generates ambiguity Ambiguity is undefined

104 Constraint Specificity Fully specify constraints Underspecification generates ambiguity Ambiguity is undefined

105 Constraint Specificity Testing and debugging

106 Constraint Specificity Testing and debugging -[UIView hasambiguouslayout]

107 Constraint Specificity Testing and debugging -[UIView hasambiguouslayout] When called on UIWindow, returns result for entire view tree

108 Constraint Specificity Testing and debugging -[UIView hasambiguouslayout] When called on UIWindow, returns result for entire view tree -[UIView _autolayouttrace]

109 Constraint Specificity Testing and debugging -[UIView hasambiguouslayout] When called on UIWindow, returns result for entire view tree -[UIView _autolayouttrace] Both can be used for unit testing

110 Table and Collection Views Impress your friends

111 Self-Sizing Cells

112 Self-Sizing Cells

113 Self-Sizing Cells

114 Self-Sizing Cells

115 Self-Sizing Cells Fully specify constraints

116 Self-Sizing Cells Fully specify constraints Width = input; height = output

117 Self-Sizing Cells

118 Self-Sizing Cells

119 Self-Sizing Cells

120 Animating Height Changes

121 Animating Height Changes 0

122 Animating Height Changes

123 Animating Height Changes

124 Animating Height Changes

125 Animating Height Changes Steps

126 Animating Height Changes Steps 1. tableview.beginupdates

127 Animating Height Changes Steps 1. tableview.beginupdates 2. Update model

128 Animating Height Changes Steps 1. tableview.beginupdates 2. Update model 3. Update cell contents

129 Animating Height Changes Steps 1. tableview.beginupdates 2. Update model 3. Update cell contents 4. tableview.endupdates

130 Fast Collection View Layout Invalidation

131 Fast Collection View Layout Invalidation

132 Fast Collection View Layout Invalidation

133 Fast Collection View Layout Invalidation

134 Fast Collection View Layout Invalidation Modify only what is needed

135 Fast Collection View Layout Invalidation Modify only what is needed 1. Invalidate on bounds change

136 Fast Collection View Layout Invalidation Modify only what is needed 1. Invalidate on bounds change 2. Build targeted invalidation context

137 Fast Collection View Layout Invalidation Modify only what is needed 1. Invalidate on bounds change 2. Build targeted invalidation context 3. Repeat as necessary

138 Summary

139 Summary Performance

140 Summary Performance User experience

141 Summary Performance User experience Future proofing

142 More Information Documentation What s New in ios Start Developing ios Apps (Swift) App Programming Guide for ios Technical Support Apple Developer Forums Developer Technical Support Curt Rothert App Frameworks Evangelist rothert@apple.com

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