Remove imageView sublayer from TableViewCell

Question

When I have an image I insert sublayer with CAGradientLayer,

...
layer.name = @\"Gradient\";
[cell.imageView.layer insertSublayer:layer atIndex:0];

Answer 1

The exception is thrown because you are changing the contents of the sublayers array while enumerating it with foreach loop. This is not something special to layers, a similar exception is thrown when you add/remove objects while enumerating any NSMutableArray.

You have various options to solve this issue

Solution 1: Stop enumerating as soon as you modify the array.

for (CALayer *layer in cell.imageView.layer.sublayers) {
    if ([layer.name isEqualToString:@"Gradient"]) {
        [layer removeFromSuperlayer];
        break;
    }
}

Solution 2: Do not enumerate the real array, instead use its copy.

NSArray* sublayers = [NSArray arrayWithArray:cell.imageView.layer.sublayers];
for (CALayer *layer in sublayers) {
    if ([layer.name isEqualToString:@"Gradient"]) {
        [layer removeFromSuperlayer];
    }
}

Solution 3: Use key value coding to keep a reference to the gradient layer.

Set it after inserting:

[cell.imageView.layer insertSublayer:layer atIndex:0];
[cell.imageView.layer setValue:layer forKey:@"GradientLayer"];

Retrieve and remove it

CALayer* layer = [cell.imageView.layer valueForKey:@"GradientLayer"];
[layer removeFromSuperlayer];
[cell.imageView.layer setValue:nil forKey:@"GradientLayer"];