Using CALayer Delegate

Question

I have a UIView whose layers will have sublayers. I\'d like to assign delegates for each of those sublayers, so the delegate method can tell the layer what to draw. My que

Answer 1

I personally voted for Dave Lee's solution above as being the most encapsulating, particularly where you have multiple layers. However; when I tried it on IOS 6 with ARC I got errors on this line and suggesting that I need a bridged cast

// [_view performSelector: selector withObject: layer withObject: (id)context];

I therefore amended Dave Lee's drawLayer method from his re-delegating delegate class to employ NSInvocation as below. All usage and ancillary functions are identical to those Dave Lee posted on his earlier excellent suggestion.

-(void) drawLayer: (CALayer*) layer inContext: (CGContextRef) context
{
    NSString* methodName = [NSString stringWithFormat: @"draw%@Layer:inContext:", layer.name];
    SEL selector = NSSelectorFromString(methodName);

    if ( ![ _view respondsToSelector: selector])
    {
        selector = @selector(drawLayer:inContext:);   
    }

    NSMethodSignature * signature = [[_view class] instanceMethodSignatureForSelector:selector];
    NSInvocation * invocation = [NSInvocation invocationWithMethodSignature:signature];

    [invocation setTarget:_view];             // Actually index 0    
    [invocation setSelector:selector];        // Actually index 1    

    [invocation setArgument:&layer atIndex:2];
    [invocation setArgument:&context atIndex:3];

    [invocation invoke];

}