ios弹出窗口自动渐渐隐藏

-(void)removeTip:(UIView *)tip

{

    [UIViewanimateWithDuration:0.5

                     animations:^{tip.alpha =0.0;}

                     completion:^(BOOL finished){ [tipsetHidden:YES]; }];

}//隐藏动画

    [self performSelector:@selector(removeTip:) withObject:tipView afterDelay:1.5f];