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)];
