iOS開發-延遲執行
阿新 • • 發佈:2019-01-30
有時候,希望某段程式碼,某個時間在一定時間後執行,這時候就要用到延遲執行。
常見的方法有以下幾種:
1.最直接的方法performSelector:withObject:afterDelay: 這種方法的缺點:每次要為延時寫一個方法
[self performSelector:@selector(scale_2) withObject:nil afterDelay:0.5f];
2.使用類別,用BOLCK執行-(void)scale_2 { UIImageView *round_2 = [[UIImageView alloc]initWithFrame:CGRectMake(105, 210, 20, 20)]; round_2.image = [UIImage imageNamed:@"round_"]; [splashView addSubview:round_2]; [self setAnimation:round_2]; }
@implementation NSObject (PerformBlockAfterDelay) - (void)performBlock:(void (^)(void))block afterDelay:(NSTimeInterval)delay { block = [[block copy] autorelease]; [self performSelector:@selector(fireBlockAfterDelay:) withObject:block afterDelay:delay]; } - (void)fireBlockAfterDelay:(void (^)(void))block { block(); } @end
3.使用GCD
void RunBlockAfterDelay(NSTimeInterval delay, void (^block)(void))
{
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, NSEC_PER_SEC*delay),
dispatch_get_current_queue(), block);
}
poolo:注意 圖中的dispatch_getcurrent_queue() 方法在ios6已經被kill了 現在用dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,0) 第一個引數是優先順序有,第二個引數為0或nil 如果要要對介面操作則使用dispatch_get_main_queue(); 參考:http://www.cnblogs.com/guwandong/archive/2012/08/08/2626211.
[程式碼]c#/cpp/oc程式碼:
[UIView animateWithDuration:0.0 delay:5.0 options:UIViewAnimationOptionAllowUserInteraction animations:^{
} completion:^(BOOL finished) {
//do stuff here
}];
5.使用NSOperationQueue,在應用程式的下一個主迴圈執行:
[程式碼]c#/cpp/oc程式碼:
1 |
[[NSOperationQueue mainQueue] addOperationWithBlock:aBlock]; |