layer.mask gradient is Solid in iOS7

Question

The next code was working fine in ios6. It is supposed to apply a top and bottom inner alpha gradient to a view:

CAGradientLayer * gradient = [CAGradientLayer layer];
gradient.frame = self.bounds;
gradient.colors = [NSArray arrayWithObjects:(id)[[UIColor clearColor] CGColor],
                   (id)[[UIColor whiteColor]CGColor],
                   (id)[[UIColor whiteColor]CGColor],
                   (id)[[UIColor clearColor] CGColor],
                   nil];

gradient.startPoint = CGPointMake(0.5, 0.0);
gradient.endPoint = CGPointMake(0.5, 1.0);
gradient.locations = [NSArray arrayWithObjects:@0,@(val),@(1.-val),@1,nil];

self.layer.mask = gradient;

BUT! If I run this code in iOS7, instead of a nice blending alpha gradient the "transparent" parts of the gradient are solid white.

One problem I have had with using built in colors is the number of color components the color has. White, gray, and black have 2 color components while others have 4. try to change your whites to `[UIColor colorWithRed:green:blue:alpha]` instead of built in colors. It may not help, but something to try. — Putz1103, Oct 15 '13 at 15:43
Thanks for the response. I tried: `gradient.colors = [NSArray arrayWithObjects: (id)[[UIColor colorWithRed:0 green:0 blue:0 alpha:0] CGColor], (id)[[UIColor colorWithRed:0 green:0 blue:0 alpha:1]CGColor], (id)[[UIColor colorWithRed:0 green:0 blue:0 alpha:1]CGColor], (id)[[UIColor colorWithRed:0 green:0 blue:0 alpha:0] CGColor], nil];` but got the same results. — Mephes, Oct 15 '13 at 16:36

score 2 · Accepted Answer · answered Oct 15 '13 at 17:03

I would put this in comments, but the formatting would be off. This snippet of code works for me in iOS 7. You can adapt it to your needs. If it's still not working then I would say that the gradient is not the problem.

+(void)addScrollingGradientToView:(UIView*)view
{
    //add in the gradient to show scrolling
    CAGradientLayer *nextImageFade = [CAGradientLayer layer];
    nextImageFade.frame = CGRectInset(view.bounds,-10,-10);

    nextImageFade.colors = [NSArray arrayWithObjects:(id)[UIColor colorWithRed:0. green:0. blue:0. alpha:0.].CGColor,
                            [UIColor colorWithRed:0. green:0. blue:0. alpha:1.0].CGColor,
                            [UIColor colorWithRed:0. green:0. blue:0. alpha:1.0].CGColor,
                            [UIColor colorWithRed:0. green:0. blue:0. alpha:0.0].CGColor,nil];
    nextImageFade.locations = [NSArray arrayWithObjects:[NSNumber numberWithFloat:0.0],
                               [NSNumber numberWithFloat:20 / view.frame.size.height],
                               [NSNumber numberWithFloat:(view.frame.size.height - 20) / view.frame.size.height],
                               [NSNumber numberWithFloat:1.], nil];
    nextImageFade.startPoint = CGPointMake(.5, 0);
    nextImageFade.endPoint = CGPointMake(.5, 1);

    //Put in the fading last so that it is above everything else
    [view.layer setMask:nextImageFade];
}

You are totally right! but not about the code, that was not the problem. I was not setting manually the background color of the parent view, and for some reason in ios6 it was defaulted to clear (so the grandparent dark-color camed out throught the alpha) and in ios7 is defaulted to white. — Mephes, Oct 16 '13 at 08:39

layer.mask gradient is Solid in iOS7

1 Answers1