Category一些(实用)用法

--实现基本的类别扩展，用以修改属性的读写属性：
Things.h

#import <Foundation/Foundation.h>
@interface Things : NSObject
@property (assign) NSInteger Things1;
@property (readonly, assign) NSInteger Things2;
-(void)resetAllValue;
@end

Things.m

#import "Things.h"
@interface Things()
@property (assign) NSInteger Things3;
@property (readwrite, assign) NSInteger Things2;
@end
@implementation Things
@synthesize Things1;
@synthesize Things2;
@synthesize Things3;
-(void)resetAllValue{
self.Things1=1;
self.Things2=2;
self.Things3=2;
};
-(NSString *)description{
return ([NSString stringWithFormat:@"Things1=%i,Things2=%i,Things3=%i",self.Things1,self.Things2,self.Things3]);
}
@end

对于一些隐藏细节的属性，通常需要使用类别来实现代码的读写控制，如该类中的Things2属性。

--实现分布的实现类功能（多人开发／框架过大）
CategoryThing.h

@interface CategoryThing : NSObject{
NSInteger thing1;
NSInteger thing2;
NSInteger thing3;
}
@end
@interface CategoryThing(Thing1)
-(void)setThing1:(NSInteger)th1;
-(NSInteger)thing1;
@end
@interface CategoryThing(Thing2)
-(void)setThing2:(NSInteger)th2;
-(NSInteger)thing2;
@end
@interface CategoryThing(Thing3)
-(void)setThing3:(NSInteger)th3;
-(NSInteger)thing3;
@end

Thing1.m

#import "CategoryThing.h"
@implementation CategoryThing(Thing1)
-(void)setThing1:(NSInteger)th1{
thing1=th1;
};
-(NSInteger)thing1{
return thing1;
};
@end

Thing2.m Thing3.m以此类推。

--扩展系统的功能（最常见）
NSString+NumberConvertion.h

@interface NSString (NumberConvertion)
-(NSNumber *)lengthAsNumber;
@end

NSString+NumberConvertion.m

#import "NSString+NumberConvertion.h"
@implementation NSString (NumberConvertion)
-(NSNumber *)lengthAsNumber{

NSUInteger length=[self length];
return ([NSNumber numberWithUnsignedInteger:length]);

};
@end

本文出自 “JAVA积累” 博客，请务必保留此出处http://linwb.blog.51cto.com/5577836/1287887