NSString 使用方法-蒲公英云

NSString 使用方法

你的名字 2022-08-10 17:45 223阅读 0赞

1.创建对象

<1>便利构造器法

NSString *str1 = [NSString stringWithFormat:@”iPhone”];

<2>初始化构造方法

NSString *str2 = [[NSString alloc] initWithFormat:@”iPhone”];

2.求字符串长度

    NSUInteger length = \[str1 length\];
    NSLog(@"length = %lu", length);

3.获取字符串中的某个字符

    unichar ch = \[str1 characterAtIndex:6\];
    NSLog(@"%c", ch);

4.判断是否以指定的字符串开头或者以指定的字符串结尾

    初始化一个字符串str4
    NSString \*str4 = \[\[NSStringalloc\] initWithFormat:@"http://www.souhu.com"\];
    判断是否以http开头
    BOOL isPrefix = \[str4 hasPrefix:@"http"\];
    NSLog(@"isPrefix = %d", isPrefix);
    判断是否以com结尾
    BOOL isSuffix = \[str4 hasSuffix:@"com"\];
    NSLog(@"isSuffix = %d", isSuffix);
     查找指定字符串com的范围
    NSRange range = \[str4 rangeOfString:@"com"\];
    NSLog(@"%@", NSStringFromRange(range));
    输出为\{17,3\}.因为字符c下标为17, com的大小为3

5.字符串的截取

    1>获取给定下标之后后的字串,包含指定下标对应的字符.
    NSString \*str5 =\[NSString stringWithFormat:@"lanouisabigcompany"\];
    NSString \*subString1 = \[str5 substringFromIndex:5\];
    NSLog(@"%@", subString1);
    输出为:isabigcompany 注意包含从下标5开始的字符: **i**

    2>获取给定下标之前的子串,从下标为1开始,但是不包括指定下标对应的字符.
    NSString \*substring2 = \[str5 substringToIndex:1\];
    NSLog(@"%@", substring2);
    输出为:l  注意不包含开始的下标1的字符
    3>获取指定范围内的子串.
    NSString \* substring3 = \[str5 substringWithRange:NSMakeRange(0, 5)\];
    NSLog(@"%@", substring3);
    输出结果为:lanoui

7 . 字符串拼接

     NSString  \*str1 = \[NSString stringWithFormat:@"lanou"\];  //初始化
     拼接"hennan"
     NSString \*substring1 = \[str1 stringByAppendingString:@"henan"\];
     NSLog(@"substring = %@", substring1);
     输出结果为:lanouhenan
     stringByAppendingFormat可以添加格式
     NSString \*substring2 = \[str1 stringByAppendingFormat:@"henan%dban",9\];
     NSLog(@"sunstring2 = %@", substring2);
     输出结果为:lanouhenan9ban
      NSString \*substring3 = \[str1stringByAppendingFormat:@"%@", str1\];
      NSLog(@"sunstring3 = %@", substring3);
       输出结果为:lanoulanou

替换字符串

将ou替换为牛逼

NSString \*str1 = \[NSString stringWithFormat:@"lanououououoooo"\];
NSString \*str = \[str1 stringByReplacingOccurrencesOfString:@"ou"withString:@"牛逼"\];
 NSLog(@"str1 = %@", str);
 输出结果为:lan牛逼牛逼牛逼牛逼oooo

    将第一个ou替换为牛逼(替换某个区域的字符串)
    NSMakeRange快速创建一个结构体
    NSString \*strr = \[str1 stringByReplacingCharactersInRange:NSMakeRange(3, 2) withString:@"牛逼"\];
    NSLog(@"strr = %@", strr);
    输出结果:lan牛逼ouououoooo 注意:3是开始的下标,2是范围

9 .字符串比较(重点)

  <1>  NSComparisonResult result = \[@"319"compare:@"311"\];
         NSLog(@"result = %ld", result);
          result = 1 (因为319 > 311)
 <2>  NSComparisonResult result = \[@"319"compare:@"319"\];
        NSLog(@"result = %ld", result);
         result = 0 (因为319 = 311)
 <3>  NSComparisonResult result = \[@"318"compare:@"319"\];
         NSLog(@"result = %ld", result);
         result = -1 (因为318=<311)

10.字符串与数值类型转换

     int value = \[@"1a23bbb" intValue\];
     NSLog(@"%d", value);
     结果为:1
  从第一个字符开始,如果在遇到除空格之外的字符时,将空格忽略掉,继续往下找,直到遇到非数字时结束

11.数字转为字符串对象

    NSString \*str = \[NSString stringWithFormat:@"%d",9\];
    NSLog(@"str = %@", str);
    结果为:9

12.大小写转换操作

 将@"lan OU"全部转为大写
 NSString \*upper = \[@"lan OU" uppercaseString\];
  NSLog(@"upper = %@", upper);
  结果为:LAN OU
 将@"lan  OU"全部转为小写
 NSString \*lower = \[@"lan OU" lowercaseString\];
 NSLog(@"lower = %@", lower);
 结果为:lan ou
 将@"lan  OU"每个单词的首字母大写
 NSString \*shou = \[@"lan OU" capitalizedString\];
 NSLog(@"shou = %@", shou);
 结果:Lan Ou