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

[thuai]

一般写initWithFrame:如下

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

在网上看到经常有人进行这样的method swizzling，代码如下：

- (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);
}

想问下，swizzled_initWithFrame:这个方法中并没有发送[super initWithFrame]这个消息，那如何保证super initWithFrame了呢？

v2ex上大神多，请轻喷！谢谢:)

[ambitiouspei]

在load 方法里， swizzled_initWithFrame: 和 initWithFrame: 实现调换了，以后调用initWithFrame: 其实实际实现就是 swizzled_initWithFrame: -> initWithFrame: > (super) initWithFrame:

[wezzard]

樓主連 Swizzle 的目標是哪個 class 都沒有搞清楚呢

swizzled initializer 裏面訪問了 CALayer 的 designated initializer，足矣。

[thuai]

@wezzard 我只是没有写全代码而已。贴中的swizzle的目标类只要是有initWithFrame这个方法的类不是都可以么？

[wezzard]

@thuai Sorry,　我看錯了。一樓說的是對的。

[thuai]

@wezzard 没关系。