iOS: NSProxy can't hook method called inside of Class itself - ios

Question

I use NSProxy to mock a class, and want to hook all invocation of the class. But only methods called outside the class are hooked, without methods called inside the class. Below is something like my code:
In my AppDelegate.m, TBClassMock is subclass of NSProxy
TBClassMock *mock = [[TBClassMock alloc] init];
TBTestClass *foo = [[TBTestClass alloc] init];
mock.target = foo;
foo = mock;
[foo outsideCalled];
In my TBTestClass.m
- (void)outsideCalled
{
[self insideCalled];
}
- (void)insideCalled
{
}
In my TBClassMock.m
- (NSMethodSignature *)methodSignatureForSelector:(SEL)selector
{
NSLog(#"Signature: %#", NSStringFromSelector(selector));
return [self.target methodSignatureForSelector:selector];
}
-(void)forwardInvocation:(NSInvocation*)anInvocation
{
//... Do other things
[anInvocation invokeWithTarget:self.target];
}
Then I can log the invocation of [foo outsideCalled], but can't log the invocation of [self insideCalled].
I aim to do something in all invocations of the class in //... Do other things, and this way seems failed. Any explanations about this and any other method to implement my requirement? I just don't want to swizzle all methods of the class using method_exchangeImplementations as I think it's too fussy and not a good way.

Answer 1

I guess you've misunderstood the concept of NSProxy. The NSProxy stands for a class, it isn't anything in itself. The way a NSProxy is supposed to be used is, you just call all the methods on proxy as if it were the class it is standing for.
In your code, instead of:
foo = mock;
[foo outsideCalled];
Do:
[mock outsideCalled];
This is my entire code:
#import <Foundation/Foundation.h>
#interface TBTestClass : NSObject
- (void)outsideCalled;
- (void)insideCalled;
#end
#implementation TBTestClass
- (void)outsideCalled;
{
NSLog(#"TBTestClass:outsideCalled");
[self insideCalled];
}
- (void)insideCalled;
{
NSLog(#"TBTestClass:insideCalled");
}
#end
#interface TBClassMock : NSProxy
#property (retain) id target;
#end
#implementation TBClassMock
#synthesize target;
- (void)dealloc
{
self.target = nil;
}
- (id)init
{
self.target = nil;
return self;
}
-(void)forwardInvocation:(NSInvocation *)anInvocation
{
if([self.target respondsToSelector:[anInvocation selector]]){
[anInvocation invokeWithTarget:self.target];
}
}
- (NSMethodSignature*)methodSignatureForSelector:(SEL)selector
{
return [self.target methodSignatureForSelector:selector];
}
#end
int main(int argc, const char **argv)
{
#autoreleasepool {
TBClassMock *mock = [[TBClassMock alloc] init];
TBTestClass *foo = [[TBTestClass alloc] init];
mock.target = foo;
[mock outsideCalled];
[mock release];
[foo release];
}
return 0;
}
Output:
2014-10-23 05:35:06.043 a.out[25483:507] TBTestClass:outsideCalled
2014-10-23 05:35:06.047 a.out[25483:507] TBTestClass:insideCalled