UIAppearance proxy for custom objects

Question

I have a custom object, it inherits from NSObject. This object does \"some things\", one of it is creating an UIView with some UIKit objects (UILabel, UIButtons ecc ecc...)

Answer 1

Nice implementation, I slightly modified the code and created the class as a subclass of NSProxy. Using it in a project I found a memory leak:

For example: using the proxy to set global settings/appearance, each instance of that class will never reach refCount 0, so dealloc will never be called.

Leak code:

-(void)forwardInvocation:(NSInvocation *)anInvocation;
{
    [...]

    // !! This will retain also the target

    [anInvocation retainArguments];

    [...]
}

Fix:

-(void)forwardInvocation:(NSInvocation *)anInvocation
{
     [anInvocation setTarget:nil];
     [anInvocation retainArguments];

     // add the invocation to the array
     [self.invocations addObject:anInvocation];
}

-(void)startForwarding:(id)sender
{
     for (NSInvocation *invocation in self.invocations) {

         // Create a new copy of the stored invocation,
         // otherwise setting the new target, this will never be released
         // because the invocation in the array is still alive after the call

         NSInvocation *targetInvocation = [invocation copy];
         [targetInvocation setTarget:sender];
         [targetInvocation invoke];
         targetInvocation = nil;
     }
}

Copy category for NSInvocation

-(id)copy
{
     NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[self methodSignature]];
     NSUInteger numberOfArguments = [[self methodSignature] numberOfArguments];

     [invocation setTarget:self.target];
     [invocation setSelector:self.selector];

     if (numberOfArguments > 2) {
         for (int i = 0; i < (numberOfArguments - 2); i++) {
             char buffer[sizeof(intmax_t)];
             [self getArgument:(void *)&buffer atIndex:i + 2];
             [invocation setArgument:(void *)&buffer atIndex:i + 2];
         }
     }

     return invocation;
}