Applying a Gradient to CAShapeLayer

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You could use the path of your shape to create a masking layer and apply that on the gradient layer, like this:

UIView *v = [[UIView alloc] initWithFrame:self.window.frame];

CAShapeLayer *gradientMask = [CAShapeLayer layer];   
gradientMask.fillColor = [[UIColor clearColor] CGColor];
gradientMask.strokeColor = [[UIColor blackColor] CGColor];
gradientMask.lineWidth = 4;
gradientMask.frame = CGRectMake(0, 0, v.bounds.size.width, v.bounds.size.height);

CGMutablePathRef t = CGPathCreateMutable();    
CGPathMoveToPoint(t, NULL, 0, 0);
CGPathAddLineToPoint(t, NULL, v.bounds.size.width, v.bounds.size.height);

gradientMask.path = t;


CAGradientLayer *gradientLayer = [CAGradientLayer layer];
gradientLayer.startPoint = CGPointMake(0.5,1.0);
gradientLayer.endPoint = CGPointMake(0.5,0.0);
gradientLayer.frame = CGRectMake(0, 0, v.bounds.size.width, v.bounds.size.height);
NSMutableArray *colors = [NSMutableArray array];
for (int i = 0; i < 10; i++) {
    [colors addObject:(id)[[UIColor colorWithHue:(0.1 * i) saturation:1 brightness:.8 alpha:1] CGColor]];
}
gradientLayer.colors = colors;

[gradientLayer setMask:gradientMask];
[v.layer addSublayer:gradientLayer];

If you want to also use the shadows, you would have to place a “duplicate” of the shape layer under the gradient layer, recycling the same path reference.

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