笔记04 category

四 category

越靠后编译的分类方法插入的越靠前，即优先级越高，编译顺序在 compile source 里

分类的属性
1 声明 分类的属性系统只会帮你声明 set和get 方法，不会实现这两个方法，需要你自己去实现
@property (copy, nonatomic) NSString* name;

关联对象

另一种方式 
#define MJKey [NSString stringWithFormat:@"%p", self]
@implementation MJPerson (Test)

NSMutableDictionary *names_;
NSMutableDictionary *weights_;
+ (void)load
{
    weights_ = [NSMutableDictionary dictionary];
    names_ = [NSMutableDictionary dictionary];
}

- (void)setName:(NSString *)name
{
//    NSString *key = [NSString stringWithFormat:@"%p", self];
    names_[MJKey] = name;
}

- (NSString *)name
{
//    NSString *key = [NSString stringWithFormat:@"%p", self];
    return names_[MJKey];
}

- (void)setWeight:(int)weight
{
//    NSString *key = [NSString stringWithFormat:@"%p", self];
    weights_[MJKey] = @(weight);
}

- (int)weight
{
//    NSString *key = [NSString stringWithFormat:@"%p", self];
    return [weights_[MJKey] intValue];
}
@end