5. Views, Drawing, and Animation (January 19, 2010)

View Hierarchy - Manipulation

• Add/remove views in IB or using UIView methods

   - (void)addSubview:(UIView *)view; 

   - (void)removeFromSuperview;

• Manipulate the view hierarchy manually:

   - (void)insertSubview:(UIView *)view atIndex:(int)index; 

   - (void)insertSubview:(UIView *)view belowSubview:(UIView *)view; 

   - (void)insertSubview:(UIView *)view aboveSubview:(UIView *)view;

   - (void)exchangeSubviewAtIndex:(int)index 

                      withSubviewAtIndex:(int)otherIndex;

  Frame 과 Bounds 차이

  위에서 View B는 Frame 은 140,65,320,320 이고 Bounds 는 0,0,200,250

  회전이 되었어도 Frame 은 smallest rectangle 로 계산 되어짐

Manual Creation

• Views are initialized using -initWithFrame:

     CGRect frame = CGRectMake(0, 0, 200, 150);

     UIView *myView = [[UIView alloc] initWithFrame:frame]; 

• Example:

     CGRect frame = CGRectMake(20, 45, 140, 21); 

     UILabel *label = [[UILabel alloc] initWithFrame:frame];

     [window addSubview:label]; 

     [label setText:@”Number of sides:”]; 

     [label release]; 

     // label now retained by window

Defining Custom Views

• Subclass UIView 

• For custom drawing, you override:

     - (void)drawRect:(CGRect)rect; 

• For event handling, you override:

     - (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event; 

     - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; 

     - (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;  

     - (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;

     ☆ drawRect 는 직접 호출하지 않는다.

CGPath

• Two parallel sets of functions for using paths 

   ■ CGContext “convenience” throwaway functions                               ■ CGPath functions for creating reusable paths

CGContext	CGPath
CGContextMoveToPoint	CGPathMoveToPoint
CGContextAddLineToPoint	CGPathAddLineToPoint
CGContextAddArcToPoint	CGPathAddArcToPoint
CGContextClosePath	CGPathCloseSubPath
...	...

Simple Path Example(삼각형 그리기)

- (void)drawRect:(CGRect)rect 

{ 

     CGContextRef context = UIGraphicsGetCurrentContext();

     [[UIColor grayColor] set]; 

     UIRectFill ([self bounds]);

     CGContextBeginPath (context); 

     CGContextMoveToPoint (context, 75, 10); 

     CGContextAddLineToPoint (context, 10, 150);

     CGContextAddLineToPoint (context, 160, 150); 

     CGContextClosePath (context);

     [[UIColor redColor] setFill];

     [[UIColor blackColor] setStroke];

     CGContextDrawPath (context, kCGPathFillStroke);

}

UIImage

• UIKit class representing an image 

• Creating UIImages:

   ■ Fetching image in application bundle 

      ■ Use +[UIImage imageNamed:(NSString *)name] 

   ■ Include file extension in file name, e.g. @”myImage.jpg”

   ■ Read from file on disk 

      ■ Use -[UIImage initWithContentsOfFile:(NSString *)path]

   ■ From data in memory 

      ■ Use -[UIImage initWithData:(NSData *)data]

UIImageView

• UIView that draws UIImages 

• Properties include:

   ■ image 

   ■ animatedImages 

   ■ animatedDuration 

   ■ animatedRepeatCount

• contentMode property to align and scale image wrt bounds

View Animation Example

- (void)showAdvancedOptions { 

   // assume polygonView and optionsView

   [UIView beginAnimations:@”advancedAnimations” context:nil]; [UIView setAnimationDuration:0.3];

   // make optionsView visible (alpha is currently 0.0) 

   optionsView.alpha = 1.0;

   // move the polygonView down 

   CGRect polygonFrame = polygonView.frame; 

   polygonFrame.origin.y += 200; 

   polygonView.frame = polygonFrame;

   [UIView commitAnimations];

}

Knowing When Animations Finish

• UIView animations allow for a delegate

   [UIView setAnimationDelegate:myController];

• myController will have callbacks invoked before and after

   - (void)animationWillStart:(NSString *)animationID 

                                        context:(void *)context;

   - (void)animationDidStop:(NSString *)animationID 

                                        finished:(NSNumber *)finished

                                        context:(void *)context;

• Can provide custom selectors if desired, for example

   [UIView setAnimationWillStartSelector: 

                                 @selector(animationWillStart)];

   [UIView setAnimationDidStopSelector: 

                                 @selector(animationDidStop)];

Saving State Across App Launches

  (어플 자체에 설정값을 두는 건데 전역으로 값이 필요할때 쓸만할듯)

• NSUserDefaults to read and write prefs & state 

• Singleton object:

   + (NSUserDefaults *)standardUserDefaults; 

• Methods for storing & fetching common types:

   - (int)integerForKey:(NSString *)key; 

   - (void)setInteger:(int)value forKey:(NSString *)key;

   - (id)objectForKey:(NSString *)key; 

   - (void)setObject:(id)value forKey:(NSString *)key;

• Find an appropriate time to store and restore your state

출저 -

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