replace CALayer

Question

I am following this answer to create a gradient using a CALayer. The key command is

[view.layer insertSublayer:gradient atIndex:0];

My problem is that I would like to update the gradient regularly. If I call the above code repeatedly, then nothing happens as new gradients are placed under the old ones. See this answer.

My question is: how does one replace a sublayer with another one. I should probably call replaceSublayer:with:. But to do this, I need a reference to the old gradient. Is there a dynamic way of obtaining this. Something like [view.layer getSublayerAtIndex: 0]? Is the easiest way to just store a reference to the current gradient in the viewcontroller?

Ideas?

score 4 · Accepted Answer · answered May 14 '11 at 16:30

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    [[view layer] replaceSublayer:[[[view layer] sublayers] objectAtIndex:0] with:gradient];

answered May 14 '11 at 16:30

Sam

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score 3 · Answer 2 · answered May 14 '11 at 16:32

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If you want to get a sublayer, you should use this method:

[view.layer.sublayers objectAtIndex:0];

Then you can replace the sublayer via

[view.layer replaceSublayer:[view.layer.sublayers objectAtIndex:0] with:yourNewGradient];

answered May 14 '11 at 16:32

akashivskyy

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No problem! :) PS: The same method is used with subviews (but you use `subviews` array instead. – akashivskyy May 14 '11 at 16:39

score 1 · Answer 3 · answered May 14 '11 at 16:46

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Besides replacing the layer, you can just update the existing CAGradientLayer's colors, locations, and other properties to change the parameters of the displayed gradient.

answered May 14 '11 at 16:46

Anomie

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replace CALayer

3 Answers3