Category一些(實用)用法

--實現基本的類別擴展，用以修改屬性的讀寫屬性：

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

對於一些隱藏細節的屬性，通常需要使用類別來實現代碼的讀寫控制，如該類中的Things2屬性。

--實現分布的實現類功能多人開發／框架過大）

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以此類推。

--擴展系統的功能最常見）

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積累” 博客，請務必保留此出處http://linwb.blog.51cto.com/5577836/1287887