1.添加分類、利用Runtime方法交換實現(xiàn)實時監(jiān)控某個ViewController

//
//  UIViewController+Swizzling.m

#import "UIViewController+Swizzling.h"

#import @implementation UIViewController (Swizzling)

+ (void)load {

    //我們只有在開發(fā)的時候才需要查看哪個viewController將出現(xiàn)
    //所以在release模式下就沒必要進行方法的交換
#ifdef DEBUG

    //原本的viewWillAppear方法
    Method viewWillAppear = class_getInstanceMethod(self, @selector(viewWillAppear:));

    //需要替換成 能夠輸出日志的viewWillAppear
    Method logViewWillAppear = class_getInstanceMethod(self, @selector(logViewWillAppear:));

    //兩方法進行交換
    method_exchangeImplementations(viewWillAppear, logViewWillAppear);

#endif

}

- (void)logViewWillAppear:(BOOL)animated {

    NSString *className = NSStringFromClass([self class]);

    //在這里，你可以進行過濾操作，指定哪些viewController需要打印，哪些不需要打印
    if ([className hasPrefix:@"UI"] == NO) {
        NSLog(@"%@ will appear",className);
    }

    //下面方法的調(diào)用，其實是調(diào)用viewWillAppear
    [self logViewWillAppear:animated];
}

@end

2.添加分類、利用Runtime快速定位到不能釋放的Viewcontroller

#import "UIViewController+Extension.h"
#import <objc/runtime.h>

@implementation UIViewController (Extension)

#pragma mark - swizzle
+ (void)load
{
    Method method1 = class_getInstanceMethod([self class], NSSelectorFromString(@"dealloc"));
    Method method2 = class_getInstanceMethod([self class], @selector(deallocSwizzle));
    method_exchangeImplementations(method1, method2);
}

- (void)deallocSwizzle
{
    NSLog(@"???%@???被銷毀了", self);
    
    [self deallocSwizzle];
}

3.給每個viewController添加屬性

@property (copy, nonatomic) NSString *method;

static char MethodKey;

- (void)setMethod:(NSString *)method
{
    objc_setAssociatedObject(self, &MethodKey, method, OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (NSString *)method
{
    return objc_getAssociatedObject(self, &MethodKey);
}