1.截取字符串

//截取掉下标7之前的字符串

NSString *string1 = @"123456789";

string1 = [string1  substringToIndex:7];//（length为7）

NSLog(@"截取的值为：%@",string1);//输出结果为1234567

---

//截取掉下标2之后的字符串

NSString *string2 = @"123456789";

string2  = [string2 substringFromIndex:2];

NSLog(@"截取的值为：%@",string2);//输出结果为3456789

---

//截取字符串最后3位

NSString *string3 = @"123456789";

string3 = [string3 substringFromIndex:string3.length- 3];

NSLog(@"截取的值为：%@",string3);//输出结果为789

//即当截取字符串后n位时,公式为：

//string = [sting substringfromIndex:string.length-n];

2.匹配字符串

NSString *string = @"18355161287";

//匹配得到的下标

NSRange range = [string rangeOfString:@"2"];

NSLog(@"range:%@",NSStringFromRange(range));//输出结果为{8,1}

NSRange range2 = [string rangeOfString:@"12"];

NSLog(@"%@",NSStringFromRange(range2));//输出结果为{7，2}

NSString *string1 = [string substringWithRange:range];//截取范围内的字符串

NSLog(@"截取的值为：%@",string1);//输出的值为2

3.替换中间部分字符

NSString *string = @"18355161287";

NSString *numberString = [string stringByReplacingCharactersInRange:NSMakeRange(3, 4) withString:@"****"]; //隐藏手机号中间四位数

NSLog(@"%@",numberString);//输出结果为183****1287

4.分隔字符串

NSString *string = @"18355161287";

NSArray *array = [string componentsSeparatedByString:@"8"];

NSLog(@"%@",array);//输出结果(1,3551612,7)

5.拼接字符串

NSString *sting1 = @"1835516";

NSString *string2 = @"1287";

NSString *string = [string1 stringByAppendingString:string2];

//NSString *string = [NSString stringWithFormat:@"%@%@",string1,string2];

//如果是可变字符串可用：[string1 appendString:string2]

NSLog(@"%@",string); //输出结果为18355161287

6.字符串大小写转换

NSString *string1 = @"abcd123";

NSString *string2 = @"XYZQ456";

//将字符串的英文字符由小写转换成大写

NSString *bigString = [string1 uppercaseString];

NSLog(@"%@",bigString); //输出结果为ABCD123

//将字符串的英文字符由大写转换为小写

NSString *smallString = [string2 lowercaseString];

NSLog(@"%@",smallString);//输出结果为xyzq456

//将字符串的首字母改为大写

NSString *firstbig = [string1 capitalizedString];

NSLog(@"%@",firstbig);//输出结果为Abcd123

7.可变字符串的增删改查

//可变字符串拼接

NSMutableString *string = [[NSMutableString alloc]initWithString:@"123"];

[string appendString:@"45"];

NSLog(@"%@",string);//输出结果12345

//可变字符串替换

NSMutableString *string2 = [[NSMutableString alloc]initWithString:@"123"];

[string2 replaceCharactersInRange:NSMakeRange(1,2) withString:@"78"];

NSLog(@"%@",string2); //输出结果178

//可变字符串的插入

NSMutableString *string3 = [[NSMutableString alloc]initWithString:@"123"];

[string3 insertString:@"56" atIndex:1];

NSLog(@"%@",string3);//输出结果15623

//可变字符串删除字符串

NSMutableString *string4 = [[NSMutableString alloc]initWithString:@"123"];

[string4 deleteCharactersInRange:NSMakeRange(1, 1)];

NSLog(@"%@",string4);//输出结果13

8.给字符串某段字符润色

NSString *contentStr = @"已阅读并同意聚奢网平台协议";

NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:contentStr];

[str addAttribute:NSForegroundColorAttributeName value:[UIColor grayColor] range:NSMakeRange(0, 6)];

//同样如果是改变字符串中某段字体的大小可以这样写：

[str addAttribute:NSFontAttributeName value:[UIFont SystemFontOfSize:20] range:NSMakeRange(0, 6)];