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結果:current string is :bbbbbb