Question

在AFNetworking 2.0中，在UIImageView+AFNetworking中有一种方法：

+ (id <AFImageCache>)sharedImageCache

我想覆盖它并返回我的自定义对象。我还要覆盖AFImageCache中的所有方法，所以基本上我在这里制作一个新的协议。我已经考虑过方法调整，但是由于缺乏经验，我不确定它是否适用于2类。如果我的类别在AFNetworking类别之前加载，它仍然有效吗？

总之，这种方法是好的吗？我想将光盘缓存添加到内存中，我想知道哪种方式在代码质量方面最干净。

Answer 1

不要使用Categories来覆盖方法。根据文件

"If the name of a method declared in a category is the same as a
 method in the original class, or a method in another category on 
 the same class (or even a superclass), the behavior is undefined 
 as to which method implementation is used at runtime. "

请参阅＆＃34;避免类别方法名称冲突＆＃34; - ＆GT; https://developer.apple.com/library/ios/documentation/Cocoa/Conceptual/ProgrammingWithObjectiveC/ProgrammingWithObjectiveC.pdf

改为子类并覆盖该方法并使用子类？

分析您的场景，进行方法调配是有意义的。注意：确保yourCache的行为与sharedImageCache相同，否则会导致崩溃。

@implementation UIImageView (Swizzling)

      + (void)load {

                static dispatch_once_t token;
                dispatch_once(&token, ^{

                    Class myClass = [self class];

                    Method originalMethod = class_getInstanceMethod(myClass, @selector(sharedImageCache));
                    Method newMethod = class_getInstanceMethod(myClass, @selector(NewSharedImageCache:));
                    method_exchangeImplementations(originalMethod, newMethod);
                });
            }

            //This is just for sample. you can create your buffer in your own way
            static id <yourCache> yourBuffer;
            + (id <yourCache>)NewSharedImageCache
            {
                return yourBuffer;
            }

@end

CategoryA如何覆盖categoryB方法

1 个答案: