可变字符串NSMutableString

//NSMutableString是NSString的子类
//可变字符串:NSMutableString,对可变字符串做增删改操作,就会对可变字符串直接进行操作

NSMutableString *mStr1 = [NSMutableString stringWithFormat:@"hello"];

//1.*****拼接字符串****

[mStr1 appendFormat:@" world"];
        NSLog(@"mStr1 = %@",mStr1);

//2.*****删除********

[mStr1 deleteCharactersInRange:[mStr1 rangeOfString:@" world"]];
        NSLog(@"mStr1 = %@",mStr1);

//3.*****插入********

[mStr1 insertString:@" girl" atIndex:5];
        NSLog(@"mStr1 = %@",mStr1);

//可变字符串中的初始化方式(给定)

NSMutableString *mStr2 = [NSMutableString stringWithCapacity:100];
       // mStr2 = @"dfsdf";可变字符串不能直接赋值(直接赋值的字符在常量区)
        [mStr2 appendFormat:@"你真帅啊"];
        [mStr2 insertString:@"帅哥" atIndex:0];
        [mStr2 appendFormat:@"约吗?"];
        NSLog(@"mStr2=%@",mStr2);

//4.*****更改********

NSRange range3 = [mStr2 rangeOfString:@"约吗?"];
        [mStr2 replaceCharactersInRange:range3 withString:@"不约"];
        NSLog(@"mStr2=%@",mStr2);

//5.*****重置********

[mStr2 setString:@"美女,你好漂亮"];
        NSLog(@"mStr1 = %@",mStr2);