Objectivec语言 字符串类NSMutableString用法

NSMutableString 是NSString 的子类，NSMutableString有很多方法，下面是总结的几种常用的方法：

stringWithString:，类级构造方法创建NSString对象；

insertString:，插入字符串，不会创建新的对象；

appendString:，追加字符串，不会创建新的对象；

deleteCharactersInRange:，在一个范围内删除字符串，不会创建新的对象；

replaceCharactersInRange: withString:，替换字符串，不会创建新的对象。

#import <Foundation/Foundation.h> 
 
int main (int argc, const char * argv[]) {  
    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];  
        NSString *str1 = @"Objective C";  
    NSString *search,*replace;  
    NSMutableString *mstr;  
    NSRange substr;  
      
    //从不可变的字符创建可变字符串对象  
    mstr = [NSMutableString stringWithString: str1];  
    NSLog(@" %@", mstr);  
      
    //插入字符串  
    [mstr insertString: @ " Java" atIndex: 9];  
    NSLog(@" %@", mstr);  
    //具有连接效果的插入字符串  
    [mstr insertString: @ " and C++"atIndex: [mstr length]];  
    NSLog(@" %@", mstr);  
    //字符串连接方法  
    [mstr appendString: @ " and C"];  
    NSLog(@" %@", mstr);      
    //使用NSRange删除字符串  
    [mstr deleteCharactersInRange:NSMakeRange(16, 13)];  
    NSLog(@" %@", mstr);      
    //查找字符串位置  
    substr = [mstr rangeOfString: @ "string B and"];  
    if (substr.location != NSNotFound) {  
             [mstr deleteCharactersInRange: substr];  
        NSLog(@" %@", mstr);  
    }  
    //直接设置可变字符串  
 
    [mstr setString: @ "This is string A "];  
    NSLog(@" %@", mstr);  
      
    [mstr replaceCharactersInRange: NSMakeRange(8, 8)  
                        withString: @ "a mutable string "];  
    NSLog(@" %@", mstr);  
    //查找和替换  
    search = @"This is ";  
    replace = @"An example of ";  
      
    substr = [mstr rangeOfString:search];  
      
    if (substr.location != NSNotFound) {  
        [mstr replaceCharactersInRange:substr withString: replace];  
        NSLog(@" %@", mstr);  
    }  
    //查找和替换所有的情况  
    search = @"a";  
    replace = @"X";  
    substr = [mstr rangeOfString: search];  
      
    while (substr.location != NSNotFound) {  
        [mstr replaceCharactersInRange:substr withString: replace];  
        substr = [mstr rangeOfString: search];  
    }  
    NSLog(@" %@", mstr);  
          
    [pool drain];  
        return 0;  
}     

运行结果如下：

2011-09-08 16:35:26.320 2.10.1-2[3124:a0f]  Objective C  
2011-09-08 16:35:26.323 2.10.1-2[3124:a0f]  Objective Java C  
2011-09-08 16:35:26.324 2.10.1-2[3124:a0f]  Objective Java C and C++  
2011-09-08 16:35:26.324 2.10.1-2[3124:a0f]  Objective Java C and C++ and C  
2011-09-08 16:35:26.325 2.10.1-2[3124:a0f]  Objective Java CC  
2011-09-08 16:35:26.325 2.10.1-2[3124:a0f]  This is string A   
2011-09-08 16:35:26.326 2.10.1-2[3124:a0f]  This is a mutable string    
2011-09-08 16:35:26.326 2.10.1-2[3124:a0f]  An example of a mutable string    
2011-09-08 16:35:26.327 2.10.1-2[3124:a0f]  An exXmple of X mutXble string   

我们解释主要代码。语句[mstr deleteCharactersInRange:NSMakeRange(16, 13)]是删除指定范围的字符串，函数NSMakeRange 是创建NSRange结构体，其中第一个参数是位置，第二个参数是长度；语句[mstr replaceCharactersInRange: NSMakeRange(8, 8)withString: @ "a mutable string "]替换指定访问的字符串；语句[mstr deleteCharactersInRange: substr]是删除指定范围的字符串。