Proxy based Aspect Oriented Programming framework for Objective-C

Note: This framework was developed merely as a proof of concept and should be considered unstable in its current state.

Structure

An APJoinPoint represents a method execution.

An APPointCut is a predictate that matches a join point.

An APAdvice is what to do at a join point.

-- APBeforeAdvice executes before a join point.

APAfterAdvice executes after a join point.

APAfterThrowingAdvice executes if a join point throws an Exception.

APAfterAdvice sorrounds the join point and gives the advice implementation control of proceeding with the join point execution and the return value.

Usage

Check out the example project for a demo of how you could use the framework.

cd Example
pod install
open ApsaraAOP.xcworkspace

Preview

@interface MyAroundAdvice : NSObject <APAroundAdvice>
@end

@implementation MyAroundAdvice

- (id)around:(id<APProceedingJoinPoint>)joinpoint {
    // The method has not beed called yet.
    // .. Do some pre processing
    
    id returnValue = [joinpoint proceed];
    
    // .. Do some post processing
    
    return returnValue;
}

@end

...

// Simple pointcut that matches all invocations on a class
id<APPointcut> pointcut = [APBlockMatchingPointcut pointcutWithBlock:^BOOL(id target, SEL selector) {
        return [target isKindOfClass:[MyService class]];
    }];

APAspectManager *aspectManager = [APAspectManager new];
[aspectManager registerAdvice:[MyAroundAdvice new] pointcut:pointcut];

MyService *service = [aspectManager advisedProxy:[MyService new]];

// The advice will be applied on calls
NSDictionary *data = [service dataDictionary];

Limitations

Objects need to be passed through the APAspectManager in order to be proxied. That means the framework is best suited for a Dependecy Injection Container or such which has central object creation control.

Since the framework is proxy-based, method calls on self from within an object cannot be intercepted.

In the current implementation: only methods with object-type return value can be intercepted. only object-type arguments can be accessed on a JoinPoint within an advice.

Author

Erik Sundin, erik@eriksundin.se

License

ApsaraAOP is available under the MIT license. See the LICENSE file for more info.