Method的几个概念
Method包含方法名Selector、函数地址IMP、参数类型TypeEncoding。
NSLog(@" method name = %s", sel_getName(method_getName(method)));
NSLog(@" method type encode = %s", method_getTypeEncoding(method));
NSLog(@" NumberOfArguments = %d", method_getNumberOfArguments(method));
NSLog(@" ReturnType = %s", method_copyReturnType(method));
2016-04-08 20:54:59.351 OCRuntime[54195:953880] method name = setNumberProperty:
2016-04-08 20:54:59.352 OCRuntime[54195:953880] method type encode = v24@0:8@16
2016-04-08 20:54:59.352 OCRuntime[54195:953880] NumberOfArguments = 3
2016-04-08 20:54:59.352 OCRuntime[54195:953880] ReturnType = v
动态修改Method的几个接口
// 设置或交换IMP
IMP method_setImplementation(Method m, IMP imp);
void method_exchangeImplementations(Method m1, Method m2);
BOOL class_addMethod(Class cls, SEL name, IMP imp, const char *types);
// 如果原来没有这个方法，则直接添加Method，效果同class_addMethod
// 如果原来有，则替换掉原来的IMP，忽略参数类型
IMP class_replaceMethod(Class cls, SEL name, IMP imp, const char *types);
+ (void)load {
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
Class class = [self class];
// When swizzling a class method, use the following:
// Class class = object_getClass((id)self);
SEL originalSelector = @selector(viewWillAppear:);
SEL swizzledSelector = @selector(xxx_viewWillAppear:);
Method originalMethod = class_getInstanceMethod(class, originalSelector);
Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
BOOL didAddMethod =
class_addMethod(class,
originalSelector,
method_getImplementation(swizzledMethod),
method_getTypeEncoding(swizzledMethod));
if (didAddMethod) {
class_replaceMethod(class,
swizzledSelector,
method_getImplementation(originalMethod),
method_getTypeEncoding(originalMethod));
} else {
method_exchangeImplementations(originalMethod, swizzledMethod);
}
});
}
参考