ios 时间定时器 NSTimer应用demo

#import <UIKit/UIKit.h> @interface UIAlertView (extended) - (void) dismiss; @end @interface HelloController : UIViewController <UIAlertViewDelegate> { UIAlertView *baseAlert; } @end @implementation HelloController - (void) alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex { printf("User Pressed Button %d\n", buttonIndex + 1); [alertView release]; } - (void) performDismiss: (NSTimer *)timer { [baseAlert dismissWithClickedButtonIndex:0 animated:NO]; [baseAlert release]; baseAlert = NULL; } - (void) presentSheet { baseAlert = [[UIAlertView alloc] initWithTitle:@"Alert" message:@"\nMessage to user with asynchronous information" delegate:self cancelButtonTitle:nil otherButtonTitles: nil]; [NSTimer scheduledTimerWithTimeInterval:3.0f target:self selector: @selector(performDismiss:) userInfo:nil repeats:NO]; [baseAlert show]; } - (id) init { if (self = [super init]) self.title = @"Hello World"; return self; } - (void)loadView { UIView *contentView = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] applicationFrame]]; self.view = contentView; contentView.backgroundColor = [UIColor whiteColor]; [contentView release]; self.navigationItem.rightBarButtonItem = [[[UIBarButtonItem alloc] initWithTitle:@"Do It" style:UIBarButtonItemStylePlain target:self action:@selector(presentSheet)] autorelease]; } @end @interface SampleAppDelegate : NSObject <UIApplicationDelegate> @end @implementation SampleAppDelegate - (void)applicationDidFinishLaunching:(UIApplication *)application { UIWindow *window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]]; UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:[[HelloController alloc] init]]; [window addSubview:nav.view]; [window makeKeyAndVisible]; } @end int main(int argc, char *argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; int retVal = UIApplicationMain(argc, argv, nil, @"SampleAppDelegate"); [pool release]; return retVal; }