rwhookdetector's Introduction

RWHookDetector

Description

RWHookDetector is a set of utility methods to detect whether an Objective-C method is swizzled or overridden in runtime.

Background

In some big project, method swizzling is such a annoying thing when being abused everywhere. Programmers encounter unexpected behaviors caused by method swizzling, that will mislead the programmer to debug.

RWHookDetector is such a tool to detect if the method swizzling is apply on target method.

Usage

For method of your own class

examle:

@implementation MyClass
+ (void) load{
  Method ori_method = class_getInstanceMethod([MyObject class], @selector(dosth));
  Method replace_method = class_getInstanceMethod([MyObject class], @selector(dosth2));
  method_exchangeImplementations(ori_method, replace_method);
}
- (void) dosth
{
    ALERT_IF_METHOD_REPLACED;
}
- (void) dosth2
{
    //hooked! lalala
    [self dosth2];
}

ALERT_IF_METHOD_REPLACED is a macro, it will raise an exception during runtime if the method is swizzled.

For method of built-in class

example:

//here is a private category might be brought from 3rd party 
@implementation UIViewController (YouDonKnow)
- (void)viewDidLoad2 {
    [self viewDidLoad2];
}
+ (void)load {
    Method ori_method = class_getInstanceMethod([UIViewController class], @selector(viewDidLoad));
    Method replace_method = class_getInstanceMethod([UIViewController class], @selector(viewDidLoad2));
    method_exchangeImplementations(ori_method, replace_method);
}
- (void)viewDidAppear:(BOOL)animated {
}
@end


// below is the code somewhere else to detect
BOOL ret = isSiwwzledOrOverridden([UIViewController class], @selector(viewDidLoad));//YES, swizzled
ret = isSiwwzledOrOverridden([UIViewController class], @selector(viewDidAppear:));//YES, overridden
ret = isSiwwzledOrOverridden([UIViewController class], @selector(viewWillAppear:))//NO