object-c 拓展nsstring方法

 

添加文件"stringtest.h"

 

#import <Foundation/Foundation.h>

@interface NSString(addprestr)
-(NSString*)add_pre;
@end

 

添加文件"stringtest.m"

#import "stringtest.h"

@implementation NSString(addprestr)
-(NSString*)add_pre{
 NSMutableString *s=[[NSMutableString alloc]init];
 [s appendString:@"current string is :"];
 [s appendString:self];
 return s;
}

@end

 

添加引用：

#import "stringtest.h"

 

 NSString *a=[NSString stringWithString:@"bbbbbb"];
 NSString *b= [a add_pre];
 NSLog(@"%@",b);
 [b release];

 

//log结果：current string is :bbbbbb