IOS 页面统计 SWIZZLE 的简单应用

swizzle 方法 置换， 都说是 ios中的黑魔法 。以前在tabbar中 使用过，前几天 碰到页面访问统计 也使用到了。 简单 简述一下实现原理，与应用场景。
原理 : http://blog.csdn.net/yiyaaixuexi/article/details/9374411

应用场景:

@implementation UIViewController (Swizzle)- (void)customViewDidAppear:(BOOL)animated{    [self customViewDidAppear:animated];}- (void)customViewWillDisappear:(BOOL)animated{    [AVAnalytics endLogPageView:NSStringFromClass([self class])];    DLog(@"customViewWillDisappear = : %@", NSStringFromClass([self class]));    [self customViewWillDisappear:animated];}- (void)customviewWillAppear:(BOOL)animated{    DLog(@"customviewWillAppear =  : %@", NSStringFromClass([self class]));    //    [AVAnalytics start];    [AVAnalytics beginLogPageView:NSStringFromClass([self class])];    [self customviewWillAppear:animated];}+ (void)load{    swizzleAllViewController();}@endvoid swizzleAllViewController(){    Swizzle([UIViewController class], @selector(viewDidAppear:), @selector(customViewDidAppear:));    Swizzle([UIViewController class], @selector(viewWillDisappear:), @selector(customViewWillDisappear:));    Swizzle([UIViewController class], @selector(viewWillAppear:), @selector(customviewWillAppear:));}