如何对 initXXXX 这系列方法进行 methods swizzling？

- (id)initWithFrame:(CGRect)frame { if (self = [super initWithFrame]) { // do something ... } return self; } 

- (id)swizzled_initWithFrame:(CGRect)frame { // This is the confusing part (article explains this line). id result = [self swizzled_initWithFrame:frame]; // Safe guard: do we have an UIView (or something that has a layer)? if ([result respondsToSelector:@selector(layer)]) { // Get layer for this view. CALayer *layer = [result layer]; // Set border on layer. layer.borderWidth = 2; layer.borderColor = [[UIColor redColor] CGColor]; } // Return the modified view. return result; } + (void)load { Method original, swizzle; // Get the "- (id)initWithFrame:" method. original = class_getInstanceMethod(self, @selector(initWithFrame:)); // Get the "- (id)swizzled_initWithFrame:" method. swizzle = class_getInstanceMethod(self, @selector(swizzled_initWithFrame:)); // Swap their implementations. method_exchangeImplementations(original, swizzle); }