1 Aspects 简介
Aspects github地址: https://github.com/steipete/Aspects
Aspects 可以很好地实现勾取一个类或者一个对象的某个方法

+ (id<AspectToken>)aspect_hookSelector:(SEL)selector
                      withOptions:(AspectOptions)options
                       usingBlock:(id)block
                            error:(NSError **)error;

/// Adds a block of code before/instead/after the current `selector` for a specific instance.
- (id<AspectToken>)aspect_hookSelector:(SEL)selector
                      withOptions:(AspectOptions)options
                       usingBlock:(id)block
                            error:(NSError **)error;

2 使用示例
主界面如下

1.png

2.1 勾取UIViewController 类所有实例的viewWillAppear:方法
2.2 勾取UIControl 类的所有实例的sendAction:to:forEvent:方法
2.3 勾取RootViewController类的rootVC 实例的viewDidLoad 方法
代码如下

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    // Override point for customization after application launch.
    
    UIWindow *window = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
    self.window = window;
    
    RootViewController *rootVC = [[RootViewController alloc] init];
    UINavigationController *rootNav = [[UINavigationController alloc] initWithRootViewController:rootVC];
    self.window.rootViewController = rootNav;
    [self.window makeKeyAndVisible];
    
    // 勾取 UIViewController 类所有实例的viewWillAppear: 方法
    [UIViewController aspect_hookSelector:@selector(viewWillAppear:) withOptions:AspectPositionAfter usingBlock:^(id<AspectInfo> info){
        UIViewController *tempVC = (UIViewController *)info.instance;
        NSLog(@"%@ viewWillAppear",[tempVC class]);
    } error:nil];
    
    [UIControl aspect_hookSelector:@selector(sendAction:to:forEvent:) withOptions:AspectPositionBefore usingBlock:^(id<AspectInfo> info){
        UIControl *control = (UIControl *)info.instance;
        if ([control isKindOfClass:[UIButton class]]) {
            UIButton *btn = (UIButton *)control;
            NSLog(@"%@",btn.titleLabel.text);
        }
    } error:nil];
    
    // 勾取rootVC 实例的viewDidLoad 方法
    [rootVC aspect_hookSelector:@selector(viewDidLoad) withOptions:AspectPositionAfter usingBlock:^(id<AspectInfo> info){
        NSLog(@"RootViewController viewDidLoad");
    } error:nil];
    
    return YES;
}

2.4启动应用就可以看到主界面，输出log如下

3.png

可以看到有两条输出，一条是viewDidLoad的输出，一条是RootViewController viewWillAppear的输出
2.5点击第一行进入详情页面如下

2.png

4.png

可以看出又多了一条输出DetailViewController viewWillAppear的输出
2.6点击导航返回主界面，输出log如下

5.png

6.png

7.png

8.png

2.7.3输出log如下

9.png