使用UIView类提供的功能来显示动画的例子

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上一个文档，我演示了timer的使用，并且形成了一个动画，但是这个动画可扩展性不好，我们需要更好的动画实现技术，这里UIView类提供了一些基本的功能。

1.新建一个view-based Application.（在iOS5中是Single View Application）

2.加入一个小的图片，我用的是一个circle.png，长和宽都不要大于100.

3.在viewcontroller.xib上面做如下布局

4. ViewController.h文件如下：

@interface subViewAnimationViewController :UIViewController {

    

    IBOutlet UIButton *myButton;

    IBOutlet UIImageView *myIV;

}

- (IBAction)startAnimation:(id)sender;

@end

5. ViewController.m文件如下：

@implementation subViewAnimationViewController

- (void)dealloc

{

    [myIVrelease];

    [myButtonrelease];

    [superdealloc];

}

- (void)didReceiveMemoryWarning

{

   // Releases the view if it doesn't have a superview.

    [superdidReceiveMemoryWarning];

    

   // Release any cached data, images, etc that aren't in use.

}

#pragma mark - View lifecycle

/*

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

- (void)viewDidLoad

{

    [super viewDidLoad];

}

*/

- (void)viewDidUnload

{

    [myIVrelease];

    myIV = nil;

    [myButtonrelease];

    myButton = nil;

    [superviewDidUnload];

   // Release any retained subviews of the main view.

   // e.g. self.myOutlet = nil;

}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation

{

   // Return YES for supported orientations

    return (interfaceOrientation == UIInterfaceOrientationPortrait);

}

- (IBAction)startAnimation:(id)sender {

    CGRect frame = myIV.frame;

    frame.origin.y =300;

    

[UIViewbeginAnimations:@"aa"context:nil];

[UIViewsetAnimationCurve:UIViewAnimationCurveEaseIn];

[UIViewsetAnimationDuration:2.0];

[myIVsetFrame:frame];

    [UIViewsetAnimationDelegate:self];

[UIViewsetAnimationDidStopSelector:@selector(viewExchangeAnimationDidStop:finished:context:)];

[UIViewcommitAnimations];

    

}

- (void) viewExchangeAnimationDidStop:(NSString *)animationID finished:(NSNumber *)finished context:(void *)context {

   

CGRect frame =myIV.frame;

    frame.origin.y =25;

[UIViewbeginAnimations:@"aa"context:nil];

[UIViewsetAnimationCurve:UIViewAnimationCurveEaseOut];

[UIViewsetAnimationDuration:2.0];

[myIVsetFrame:frame];

[UIViewcommitAnimations];

}

@end

6.解释代码如下：

 CGRect frame = myIV.frame;

    frame.origin.y = 300;

    

[UIView beginAnimations:@"aa" context:nil];//开始一个动画

[UIView setAnimationCurve:UIViewAnimationCurveEaseIn];//设置动画先慢后快

[UIView setAnimationDuration:2.0];//设置动画持续2秒

[myIV setFrame:frame];//动画内容，从现有位置移动到frame指示的位置。

    [UIView setAnimationDelegate:self];

[UIView setAnimationDidStopSelector:@selector(viewExchangeAnimationDidStop:finished:context:)];

//上面的两句话设置，当动画结束的时候，调用本类的viewExchangeAnimationDidStop:finished:context:函数

[UIView commitAnimations];//开始动画

其他的代码就不解释了，

7.例子代码

http://download.csdn.net/detail/NickTang/3690975