Designing iphone Applications

Transcription

1 Designing iphone Applications 4

2 Two Flavors of Mail 5

3 Organizing Content 6

4 Organizing Content 6

5 Organizing Content 6

6 Organizing Content 6

7 Organizing Content Focus on your user s data 6

8 Organizing Content Focus on your user s data One thing at a time 6

9 Organizing Content Focus on your user s data One thing at a time Screenfuls of content 6

10 Patterns for Organizing Content 7

11 Patterns for Organizing Content Navigation Bar 7

12 Patterns for Organizing Content Navigation Bar Tab Bar 7

13 Navigation Bar Hierarchy of content Drill down into greater detail 8

14 Navigation Bar Hierarchy of content Drill down into greater detail 8

15 Tab Bar Self-contained modes 9

16 Tab Bar Self-contained modes 9

17 A Screenful of Content Slice of your application Views, data, logic 10

18 Parts of a Screenful Model View 11

19 Parts of a Screenful Model View Controller 11

20 Parts of a Screenful Model View Controller 12

21 Model-View-Controller (Why and How?) 13

22 Why Model-View-Controller? Ever used the word spaghetti to describe code? Clear responsibilities make things easier to maintain Avoid having one monster class that does everything 14

23 Why Model-View-Controller? Ever used the word spaghetti to describe code? Clear responsibilities make things easier to maintain Avoid having one monster class that does everything 14

24 Why Model-View-Controller? Separating responsibilites also leads to reusability By minimizing dependencies, you can take a model or view class you ve already written and use it elsewhere Think of ways to write less code 15

25 Communication and MVC How should objects communicate? Which objects know about one another? 16

26 Communication and MVC How should objects communicate? Which objects know about one another? Model Example: Polygon class Not aware of views or controllers Typically the most reusable Communicate generically using... Key-value observing Model Notifications 17

27 Communication and MVC How should objects communicate? Which objects know about one another? View Example: PolygonView class Not aware of controllers, may be aware of relevant model objects Also tends to be reusable Communicate with controller using... Target-action View Delegation 18

28 Communication and MVC How should objects communicate? Which objects know about one another? Controller Knows about model and view objects The brains of the operation Manages relationships and data flow Typically app-specific, so rarely reusable Controller 19

29 Communication and MVC Model View Controller 20

30 Communication and MVC Model View Controller 20

31 Communication and MVC Model View KVO, notifications target-action, delegation Controller 20

32 View Controllers CPRE 388

33 View Controllers Manage views in model view controller design template. Many types: custom view controller; container view controller; modal view controller.

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35 Custom View controllers At least one per app. Subclass of UIViewController UIViewController instances have data (member vars), view through member vars pointing to IBOutlets, action methods, and any other view control related activities.

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37 Table View Controllers Table of data Selection management Row editing Table configuration Table view object managed by UITableViewController

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39 Navigation View Controller Container view controller to manage data/views organized hierarchically. Instance of class UINavigationController Manages multiple view controllers but also some views a navigation bar current location in data hierarchy; back button; custom controls for the current view

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41 Tab Bar Controller Container controller UITabBarController class Present same data differently or present different types of data If there are more views than the space for tabs on the tab bar, Tab bar controller also manages tab bar

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43 Modal View Controllers Just a mode of presenting a VC from another VC Generalization of container VCs. Typical present a view to gather some user information picking a picture for a calendar contact

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45 Anatomy: Custom View Controller

46 Custom VC essential tasks You must configure the view to be loaded by your view controller You must decide which orientations your view controller supports You must clean up the memory that is managed by your view controller

47 Typical VC Members Member variables pointing to the objects containing the data to be displayed by the corresponding views Member variables (or outlets) pointing to key view objects with which your view controller must interact Action methods that perform tasks associated with buttons and other controls in the view hierarchy Custom tasks

48 View Management Cycles Load cycle Unload cycle

49 Load Cycle Some part of your application asks for the view in the view controller s view property If the view is not currently in memory, the view controller calls its loadview method The loadview method responsible for loading a non nil view

50 loadview If over ridden, you are responsible for creating all views, and assigning a non nil view property. Default implementation uses nibname and nibbundle. If no nib file found, creates empty UIView object and assigns it to view property.

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53 Creating a VC (void)displaymodalview { MyViewController* vc = [[[MyViewController alloc] initwithnibname:@"myviewcontroller" bundle:nil] autorelease]; [self presentmodalviewcontroller:vc animated:yes]; }

54 Class MyViewController : UIViewController { id mybutton; id mytextfield; (nonatomic) IBOutlet id (nonatomic) IBOutlet id mytextfield; (IBAction)myAction:(id)sender;

55 Contents of MyViewConroller.nib

56 (void)loadview { self.wantsfullscreenlayout = YES; MetronomeView *view = [[MetronomeView alloc] initwithframe:[uiscreen mainscreen].applicationframe]; view.metronomeviewcontroller = self; self.view = view; self. [view release]; }

57 When overriding the loadview method to create your views programmatically, you should not call super. Doing so initiates the default view loading behavior and is usually just a waste of CPU cycles. Your own implementation of the loadview method should do all the work that is needed to create a root view and subviews for your view controller.

58 Cleaning up after Unloading Clean up references to view objects in: The dealloc method The viewdidunload method

59 View Orientations At minimum, portrait orientation needs to be supported by default. Additional orientations can be supported by a view controller (optionally). Both views and view controllers have to do additional work.

60 Orientations Override your view controller s shouldautorotatetointerfaceorientation: method Configure the autoresizing mask for each view in your view controller s view hierarchy

61 Orientation When the device orientation changes, systems sends out UIDeviceOrientationDidChangeNotification notification UIKit framework intercepts this notification and uses it to update your interface orientation automatically The window object does much of the work associated with changing the current orientation

62 Orientation Polls view controllers at the front to see if they support the alternate orientation. These view controllers should ask their subviews (controllers) about their support for the new (proposed) orientation.

63 Declaring the Supported Interface Orientations (BOOL)shouldAutorotateToInterfaceOrientation:( UIInterfaceOrientation)orientation { if ((orientation == UIInterfaceOrientationPortrait) (orientation == UIInterfaceOrientationLandscapeLeft)) return YES; return NO; }

64 View Resizing on Re Orientation the bounds of the affected views are modified automatically according to their autoresizing mask. you might use these notifications to make the following types of changes: Show or hide views that are specific to a particular orientation Show or hide views that are specific to a particular orientation Show or hide views that are specific to a particular orientation

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66 Memory Management critical data structures required by your view controller; Initialization methods; Creating view objects; loadview Allocating or loading data to be displayed in your view; viewdidload

67 Releasing refs to view objects; viewdidunload; Releasing the data not needed when view is not displayed; viewdidunload; Responding to low memory notifications; didreceivememorywarning Releasing critical data structures required by your view controller; dealloc

68 View Controllers 21

69 Problem: Managing a Screenful Controller manages views, data and application logic Apps are made up of many of these Would be nice to have a well-defined starting point A la UIView for views Common language for talking about controllers 22

70 Problem: Building Typical Apps Some application flows are very common Navigation-based Tab bar-based Combine the two Don t reinvent the wheel Plug individual screens together to build an app 23

71 UIViewController Basic building block Manages a screenful of content Subclass to add your application logic View Controller Views Data Logic 24

72 UIViewController Basic building block Manages a screenful of content Subclass to add your application logic 24

73 Your and Our View Controllers Create your own UIViewController subclass for each screenful Plug them together using existing composite view controllers 25

74 Your and Our View Controllers Create your own UIViewController subclass for each screenful Plug them together using existing composite view controllers Navigation Controller View Controller View Controller View Controller 25

75 Your and Our View Controllers Create your own UIViewController subclass for each screenful Plug them together using existing composite view controllers View Controller Tab Bar Controller View Controller View Controller 25

76 Your View Controller Subclass 26

77 Your View Controller Subclass #import MyViewController : UIViewController { // A view controller will usually // manage views and data NSMutableArray *mydata; UILabel *mylabel; } 26

78 Your View Controller Subclass #import MyViewController : UIViewController { // A view controller will usually // manage views and data NSMutableArray *mydata; UILabel *mylabel; } // Expose some of its contents to (readonly) NSArray *mydata; 26

79 Your View Controller Subclass #import MyViewController : UIViewController { // A view controller will usually // manage views and data NSMutableArray *mydata; UILabel *mylabel; } // Expose some of its contents to (readonly) NSArray *mydata; // And respond to actions - (void)dosomeaction:(id)sender; 26

80 The View in View Controller 27

81 The View in View Controller UIViewController superclass has a view (retain) UIView *view; 27

82 The View in View Controller UIViewController superclass has a view (retain) UIView *view; Loads lazily On demand when requested Can be purged on demand as well (low memory) 27

83 The View in View Controller UIViewController superclass has a view (retain) UIView *view; Loads lazily On demand when requested Can be purged on demand as well (low memory) Sizing and positioning the view? Depends on where it s being used Don t make assumptions, be flexible 27

84 When to call -loadview? 28

85 When to call -loadview? Don t do it! 28

86 When to call -loadview? Don t do it! Cocoa tends to embrace a lazy philosophy Call -release instead of -dealloc Call -setneedsdisplay instead of -drawrect: 28

87 When to call -loadview? Don t do it! Cocoa tends to embrace a lazy philosophy Call -release instead of -dealloc Call -setneedsdisplay instead of -drawrect: Allows work to be deferred or coalesced Performance! 28

88 Creating Your View in Code 29

89 Creating Your View in Code Override -loadview Never call this directly // Subclass of UIViewController - (void)loadview { } 29

90 Creating Your View in Code Override -loadview Never call this directly Create your views // Subclass of UIViewController - (void)loadview { MyView *myview = [[MyView alloc] initwithframe:frame]; } [myview release]; 29

91 Creating Your View in Code Override -loadview Never call this directly Create your views Set the view property // Subclass of UIViewController - (void)loadview { MyView *myview = [[MyView alloc] initwithframe:frame]; self.view = myview; // The view controller now owns the view [myview release]; } 29

92 Creating Your View in Code Override -loadview Never call this directly Create your views Set the view property Create view controller with -init // Subclass of UIViewController - (void)loadview { MyView *myview = [[MyView alloc] initwithframe:frame]; self.view = myview; // The view controller now owns the view [myview release]; } 29

93 Creating Your View with Interface Builder 30

94 Creating Your View with Interface Builder Lay out a view in Interface Builder 30

95 Creating Your View with Interface Builder Lay out a view in Interface Builder File s owner is view controller class 30

96 Creating Your View with Interface Builder Lay out a view in Interface Builder File s owner is view controller class Hook up view outlet 30

97 Creating Your View with Interface Builder Lay out a view in Interface Builder File s owner is view controller class Hook up view outlet Create view controller with -initwithnibname:bundle: 30

98 View Controller Lifecycle 32

99 View Controller Lifecycle - (id)initwithnibname:(nsstring *)nibname bundle:(nsbundle *)bundle { if (self == [super init...]) { // Perform initial setup, nothing view-related mydata = [[NSMutableArray alloc] init]; self.title Foo ; } return self; } 32

100 View Controller Lifecycle 33

101 View Controller Lifecycle - (void)viewdidload { // Your view has been loaded // Customize it here if needed view.someweirdproperty = YES; } 33

102 View Controller Lifecycle 34

103 View Controller Lifecycle - (void)viewwillappear:(bool)animated { [super viewwillappear:animated]; } // Your view is about to show on the screen [self beginloadingdatafromtheweb]; [self startshowingloadingprogress]; 34

104 View Controller Lifecycle 35

105 View Controller Lifecycle - (void)viewwilldisappear:(bool)animated { [super viewwilldisappear:animated]; } // Your view is about to leave the screen [self rememberscrollposition]; [self savedatatodisk]; 35

106 Loading & Saving Data Lots of options out there, depends on what you need NSUserDefaults Property lists CoreData SQLite Web services Covering in greater depth in Lecture 9 on 4/29 36

107 More View Controller Hooks Automatically rotating your user interface Low memory warnings 38

108 Supporting Interface Rotation 39

109 Supporting Interface Rotation - (BOOL)shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation)interfaceOrientation { // This view controller only supports portrait return (interfaceorientation == UIInterfaceOrientationPortrait); } 39

110 Supporting Interface Rotation 40

111 Supporting Interface Rotation - (BOOL)shouldAutorotateToInterfaceOrientation: (UIInterfaceOrientation)interfaceOrientation { // This view controller supports all orientations // except for upside-down. return (interfaceorientation!= UIInterfaceOrientationPortraitUpsideDown); } 40

112 Autoresizing Your Views 42

113 Autoresizing Your Views view.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleHeight; 42

114 Autoresizing Your Views view.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleHeight; 42

115 Autoresizing Your Views view.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleHeight; view.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleTopMargin; 42

116 Autoresizing Your Views view.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleHeight; view.autoresizingmask = UIViewAutoresizingFlexibleWidth UIViewAutoresizingFlexibleTopMargin; 42