如何在iPhone中跟踪长按手指？

Question

如何在iPhone屏幕上跟踪触摸事件2秒钟.就像在Safari中保存图像一样,添加到UIWebView中的图像？

Answer 1

+scheduledTimerWithTimeInterval:target:selector:userInfo:repeats:在视图的-touchesBegan:withEvent:方法中创建NSTimer ,并取消它(使用-invalidate)in -touchesEnded:withEvent:.如果其选择器指向的方法被调用,则用户将其手指放在视图上,无论您将计时器的间隔设置为何时.例:

接口(.h):

@interface MyView : UIView
    ...
    NSTimer *holdTimer;
@end

实施(.m):

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)evt
{
    [holdTimer invalidate];
    holdTimer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(touchWasHeld) userInfo:nil repeats:NO];
}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)evt
{
    [holdTimer invalidate];
    holdTimer = nil;
}

- (void)touchWasHeld
{
    holdTimer = nil;
    // do your "held" behavior here
}