Objective-C Method Swizzle 使用过程中需要注意的问题

Test_OC_Method_Swizzle.m

//
//  main.m
//  testDispatch
//
//  Created by guoyiyuan on 2019/6/6.
//  Copyright © 2019 guoyiyuan. All rights reserved.
//

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

@interface Father : NSObject
-(void)work;
@end
@implementation Father
-(void)work{
	NSLog(@"父亲得赚钱养家");
}
@end

@interface Son : Father
@end

@implementation Son

BOOL simple_Swizzle(Class aClass, SEL originalSel,SEL swizzleSel){
	
	Method originalMethod = class_getInstanceMethod(aClass, originalSel);
	Method swizzleMethod = class_getInstanceMethod(aClass, swizzleSel);
	method_exchangeImplementations(originalMethod, swizzleMethod);
	
	return YES;
}
BOOL best_Swizzle(Class aClass, SEL originalSel,SEL swizzleSel){
	
	Method originalMethod = class_getInstanceMethod(aClass, originalSel);
	Method swizzleMethod = class_getInstanceMethod(aClass, swizzleSel);
	BOOL didAddMethod = class_addMethod(aClass, originalSel, method_getImplementation(swizzleMethod), method_getTypeEncoding(swizzleMethod));
	if (didAddMethod) {
		class_replaceMethod(aClass, swizzleSel, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
	}else{
		method_exchangeImplementations(originalMethod, swizzleMethod);
	}
	
	return YES;
}

@end

添加如下代码，结果会是怎样呢?

@implementation Son (Swizzle)

-(void)son_work{
	[self son_work];
	NSLog(@"son分类里的son_work");
}

+(void)load{
	NSLog(@"Swizzle 被调用");
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		simple_Swizzle([self class], NSSelectorFromString(@"work"), @selector(son_work));
	});
}

@end

int main() {
	Son *son = [Son new];
	[son work];
}

修改上面程序:

-(void)son_work{
	[self work];
	NSLog(@"son分类里的son_work");
}

导致的son_work递归调用问题如何解决：

1. 修改son_work方法：

-(void)son_work{
	[self son_work];
	NSLog(@"son分类里的son_work");
}

2. Son类中新增方法:

-(void)work{
	NSLog(@"破除循环调用");
}

添加以下代码，结果会是怎样呢?

@implementation Son (Swizzle_another)

+(void)load {
	NSLog(@"Swizzle_another 被调用");
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		simple_Swizzle([self class], NSSelectorFromString(@"work"), @selector(son_another_work));
	});
}

-(void)son_another_work {
	[self son_work];
	NSLog(@"son分类里的son_another_work");
}

@end

@implementation Son (Swizzle)

-(void)son_work{
	[self son_work];
	NSLog(@"son分类里的son_work");
}

+(void)load{
	NSLog(@"Swizzle 被调用");
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		simple_Swizzle([self class], NSSelectorFromString(@"work"), @selector(son_work));
	});
}

@end

int main() {
	Son *son = [Son new];
	[son work];
}

添加以下代码，结果会是怎样呢?

@implementation Son (Swizzle)

-(void)son_work{
	[self son_work];
	NSLog(@"son分类里的son_work");
}

+(void)load{
	NSLog(@"Swizzle 被调用");
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		simple_Swizzle([self class], NSSelectorFromString(@"work"), @selector(son_work));
	});
}

@end

@implementation Son (Swizzle_another)

+(void)load {
	NSLog(@"Swizzle_another 被调用");
	static dispatch_once_t onceToken;
	dispatch_once(&onceToken, ^{
		simple_Swizzle([self class], NSSelectorFromString(@"work"), @selector(son_work));
	});
}

-(void)son_work {
	[self son_work];
	NSLog(@"son分类里的son_another_work");
}

@end

int main() {
	Son *son = [Son new];
	[son work];
}