Foundation框架中的NSMutableString对象

NSMutableString 可变字符串对象

1.字符串对象本身不可以被修改 

2.NSMutableString 是NSString的子类继承NSString 

3.创建可变字符串对象 字符串对象本身可以被修改 

4.可变字符串对象可以直接调用不可变字符串对象的方法

创建一个可变字符串

1.直接创建

        NSMutableString *mstr ;
        [mstr setString:str3];
        NSLog(@"mstr = %@", mstr);

2.由不可变字符串转换为可变字符串

        NSString *str3 = @"This is string A";
        NSString *str4 = @"This is string B";
        NSMutableString *mstr ;
   
        mstr = [NSMutableString stringWithString:str3];
        NSLog(@"mstr = %@", mstr);

可变字符串的操作

    //在指定位置增加字符串
    //- (void)insertString:(NSString *)aString atIndex:(NSUInteger)loc;
    [str1 insertString:@" welcome" atIndex:5];
    NSLog(@"str1 = %@",str1);
    
    //删除指定范围内的字符
    //- (void)deleteCharactersInRange:(NSRange)range
    [str1 deleteCharactersInRange:NSMakeRange(6, 3)];
    NSLog(@"str1 = %@",str1);
    
    //在字符串末尾追加字符串
    //- (void)appendString:(NSString *)aString;
    [str1 appendString:@" baidu"];
    NSLog(@"str1 = %@",str1);
    
    //格式化追加字符串
    //- (void)appendFormat:(NSString *)format, ... NS_FORMAT_FUNCTION(1,2);
    [str1 appendFormat:@"%d%s",123,".com"];
    NSLog(@"str1 = %@",str1);
    //替换
    [mstr replaceCharactersInRange:NSMakeRange(3, 4) withString: @" hello "];
    NSLog(@"mstr = %@",mstr);
    //查找
    NSRange range1 = [mstr rangeOfString:@"A"];
    NSLog(@"range1.location = %lu ,range.length = %lu ", range1.location, range1.length);