ios runtime swizzle

最新推荐文章于 2024-10-16 19:53:25 发布

zhangping871

最新推荐文章于 2024-10-16 19:53:25 发布

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本文介绍了一种Objective-C中常用的方法交换技术，通过修改类方法的实现来达到修改类行为的目的。具体展示了如何使用`method_exchangeImplementations`来交换两个实例方法`objectAtIndex:`和`hm_objectAtIndex:`以及`addObject:`和`hm_addObject:`，以此改变`NSArray`和`NSMutableArray`的行为。

<pre name="code" class="objc">#import <objc/runtime.h>

<img src="https://img-blog.youkuaiyun.com/20150329222437671?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvemhhbmdwaW5nODcx/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />

@implementation NSObject(Extension)
+ (void)swizzleClassMethod:(Class)class originSelector:(SEL)originSelector otherSelector:(SEL)otherSelector
{
    Method otherMehtod = class_getClassMethod(class, otherSelector);
    Method originMehtod = class_getClassMethod(class, originSelector);
    // 交换2个方法的实现
    method_exchangeImplementations(otherMehtod, originMehtod);
}

+ (void)swizzleInstanceMethod:(Class)class originSelector:(SEL)originSelector otherSelector:(SEL)otherSelector
{
    Method otherMehtod = class_getInstanceMethod(class, otherSelector);
    Method originMehtod = class_getInstanceMethod(class, originSelector);
    // 交换2个方法的实现
    method_exchangeImplementations(otherMehtod, originMehtod);
}
@end

@implementation NSArray(Extension)
+ (void)load
{
    [self swizzleInstanceMethod:NSClassFromString(@"__NSArrayI") originSelector:@selector(objectAtIndex:) otherSelector:@selector(hm_objectAtIndex:)];
}

- (id)hm_objectAtIndex:(NSUInteger)index
{
    if (index < self.count) {
        return [self hm_objectAtIndex:index];
    } else {
        return nil;
    }
}

@end

@implementation NSMutableArray(Extension)
+ (void)load
{
    [self swizzleInstanceMethod:NSClassFromString(@"__NSArrayM") originSelector:@selector(addObject:) otherSelector:@selector(hm_addObject:)];
    [self swizzleInstanceMethod:NSClassFromString(@"__NSArrayM") originSelector:@selector(objectAtIndex:) otherSelector:@selector(hm_objectAtIndex:)];
}

- (void)hm_addObject:(id)object
{
    if (object != nil) {
        [self hm_addObject:object];
    }
}

- (id)hm_objectAtIndex:(NSUInteger)index
{
    if (index < self.count) {
        return [self hm_objectAtIndex:index];
    } else {
        return nil;
    }
}
@end