友盟SDK有一个私有类UMAOCTools，在类方法setupHook中hook了UIViewController的viewDidDisapper方法。在新的viewDidDisapper中却没有放行原方法，导致项目中其它地方无法再次hook此方法。

解决办法如下

#import <objc/runtime.h>

@implementation NSObject (FuckUM)

static void swizzleClassMethod(Class c, SEL orig, SEL new) {
    Method origMethod = class_getClassMethod(c, orig);
    Method newMethod = class_getClassMethod(c, new);
    c = object_getClass((id)c);
    if(class_addMethod(c, orig, method_getImplementation(newMethod), method_getTypeEncoding(newMethod)))
        class_replaceMethod(c, new, method_getImplementation(origMethod), method_getTypeEncoding(origMethod));
    else
        method_exchangeImplementations(origMethod, newMethod);
}

+ (void)load {
    swizzleClassMethod(NSClassFromString(@"UMAOCTools"), NSSelectorFromString(@"setupHook"), @selector(doNothing));
}

+ (void)doNothing {
}

@end