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我們很難想像一個不包含動畫的iOS應用程序，一個iOS遊戲更是不可能沒有動畫，因此我從今天開始一個新的課題－－－如何寫動畫相關的代碼。
這裏的第一篇文章其實和iOS提供的動畫API沒有關係，只是使用定時器來形成一個動畫，因爲這是動畫的最記本實現方式。所以這個例子也是順便演示一下定時器如何使用。
1.新建一個view-based Application.（在iOS5中是Single View Application）
2.加入一個小的圖片，比如1.png，長和寬都不要大於100.
3.在viewcontroller.xib上面做如下佈局
4.爲它們增加相應的控制指針，並對兩個button的touch up inside事件響應，最後形成的viewcontroller.h文件如下：
@interface tTimerAnimationViewController : UIViewController {
NSTimer *aniTimer;
IBOutlet UIImageView *myIV;
IBOutlet UIButton *startButton;
IBOutlet UIButton *stopButton;
int directionDelta;
}
- (IBAction)stop:(id)sender;
- (IBAction)start:(id)sender;
- (void)timerFunc;
@end
5.下面是viewcontroller.m文件，
@implementation tTimerAnimationViewController
- (void)dealloc
{
[myIV release];
[startButton release];
[stopButton release];
[aniTimer invalidate];
[super dealloc];
}
- (void)didReceiveMemoryWarning
{
// Releases the view if it doesn't have a superview.
[super didReceiveMemoryWarning];
// 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];
stopButton.enabled = NO;
directionDelta = 2;
}
- (void)viewDidUnload
{
[myIV release];
myIV = nil;
[startButton release];
startButton = nil;
[stopButton release];
stopButton = nil;
[super viewDidUnload];
// 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)stop:(id)sender {
startButton.enabled = YES;
stopButton.enabled = NO;
[aniTimer invalidate];
aniTimer = nil;
}
- (IBAction)start:(id)sender {
startButton.enabled = NO;
stopButton.enabled = YES;
aniTimer = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(timerFunc) userInfo:nil repeats:YES];
}
- (void)timerFunc
{
CGPoint center = myIV.center;
if(center.y >450)
directionDelta = -2;
if(center.y < 30)
directionDelta = 2;
center.y += directionDelta;
myIV.center = center;
}
@end
6.解釋如下：
aniTimer = [NSTimer scheduledTimerWithTimeInterval:0.01 target:self selector:@selector(timerFunc) userInfo:nil repeats:YES];
上面的這句話啓動一個定時器，每0.01秒調用一次，定時器觸發的函數是self的timerFunc。userInfo是傳入到timerFunc的參數，repeats是標識是否重複調用這個定時器。
相關代碼在這裏：
http://download.csdn.net/download/NickTang/3690782