问卡在UIImageView掩蔽多个图像中

EN

- (void)addGradientToView:(UIView *)view
{
    CAGradientLayer *gradient = [CAGradientLayer layer];
    gradient.frame = CGRectMake(0, view.frame.size.height * 0.8, view.frame.size.width, view.frame.size.height * 0.2);
    gradient.colors = @[(id)[[UIColor clearColor] CGColor],
                        (id)[[UIColor blackColor] CGColor]];
    [view.layer insertSublayer:gradient atIndex:0];
}