gistfile1.m

//
//  main.m
//  Probie
//
//  Created by Seth Willits on 11/19/14.
//  Copyright (c) 2014 Araelium Group. All rights reserved.
//

#import <Foundation/Foundation.h>
#import <objc/runtime.h>
#import <objc/message.h>


void MethodSwizzle(Class c, SEL orig, SEL new)
{
	Method origMethod = class_getInstanceMethod(c, orig);
	Method newMethod = class_getInstanceMethod(c, new);
	if (class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod))) {
		class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
	} else {
		method_exchangeImplementations(origMethod, newMethod);
	}
}



@interface Probie : NSObject
@end

@implementation Probie

#define BEGIN_PROBIE \
		NSTimeInterval _profilingT = NSDate.timeIntervalSinceReferenceDate;

#define END_PROBIE \
		_profilingT = (NSDate.timeIntervalSinceReferenceDate - _profilingT); \
		if (_profilingT > 0.01) NSLog(@"[PROF] %@: %f", NSStringFromSelector(_cmd), _profilingT); \
		
+ (void)probeClass:(Class)class selector:(SEL)selector
{
	SEL newSel = NSSelectorFromString([@"swizzled_" stringByAppendingString:NSStringFromSelector(selector)]);
	Method originalMethod = class_getInstanceMethod(class, selector);
	
	
	SEL swizzledSelector = [self swizzledSelectorForClass:class selector:selector];
	if (!swizzledSelector) {
		NSLog(@"Probie can't probe [%@ %@] because no swizzle equivalent exists", NSStringFromClass(class), NSStringFromSelector(selector));
		return;
	}
	
	
	IMP newImplementation = method_getImplementation(class_getInstanceMethod(self, swizzledSelector));
	
	if (class_addMethod(class, newSel, newImplementation, method_getTypeEncoding(originalMethod))) {
		Method newMethod = class_getInstanceMethod(class, newSel);
		method_exchangeImplementations(originalMethod, newMethod);
	}
}



+ (SEL)swizzledSelectorForClass:(Class)class selector:(SEL)selector
{
	unsigned int count = 0;
	Method * methods = class_copyMethodList(self, &count);
	SEL swizzledSelector = nil;
	
	Method originalMethod = class_getInstanceMethod(class, selector);
	const char * originalMethodTypes = method_getTypeEncoding(originalMethod);
	
	if (methods) {
		for (unsigned int i = 0; i < count; i++) {
			struct objc_method_description * desc = method_getDescription(methods[i]);
			NSString * name = NSStringFromSelector(desc->name);
			if ([name hasPrefix:@"swizzled_"]) {
				if (strcmp(originalMethodTypes, desc->types) == 0) {
					swizzledSelector = desc->name;
					break;
				}
			}
		}
		
		free(methods);
	}
	
	return swizzledSelector;
}



- (void)swizzled_void_args0
{
	BEGIN_PROBIE
	{
		SEL newSel = NSSelectorFromString([@"swizzled_" stringByAppendingString:NSStringFromSelector(_cmd)]);
		((void (*)(id, SEL))objc_msgSend)(self, newSel /* args */);
	}
	END_PROBIE
}



- (int)swizzled_int_args0
{
	int retval;
	
	BEGIN_PROBIE
	{
		SEL newSel = NSSelectorFromString([@"swizzled_" stringByAppendingString:NSStringFromSelector(_cmd)]);
		retval = ((int (*)(id, SEL))objc_msgSend)(self, newSel /* args */);
	}
	END_PROBIE
	
	return retval;
}


@end




@interface Foo : NSObject
@end

@implementation Foo

- (void)test1
{
	usleep(1e5);
}

- (int)test2
{
	usleep(1e5);
	return 2;
}

- (void)test3:(id)a
{
	usleep(1e5);
}

@end


int main(int argc, const char * argv[])
{
	@autoreleasepool {
		
		[Probie probeClass:[Foo class] selector:@selector(test1)];
		[Probie probeClass:[Foo class] selector:@selector(test2)];
		[Probie probeClass:[Foo class] selector:@selector(test3:)];
		
		
		Foo * foo = [[Foo alloc] init];
		[foo test1];
		[foo test2];
	}
    return 0;
}