NSString NSMutableString

Objective-C 入门第二章 NSString NSMutableString

NSString

创建字符串 获取字符串字符串拼接大小写转换判断前后缀判断字符是否相等 查找字符串字符串替换读取文件

NSMutableString

添加字符串 - 追加字符串 - 替换字符串 - 插入字符串 - 删除字符串

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创建字符串

NSString 有三种常见的初始化化方式。

1.简单初始化

NSString *str = @"简单初始化"; NSLog(@"str = %@",str);

2.常规初始化

NSString *str1 = [[NSString alloc] initWithFormat:@"常规初始化"]; NSLog(@"str1 = %@",str1);

3.便利初始化

NSString *str2 = [NSString stringWithFormat:@"便利初始化"]; NSLog(@"str2 = %@",str2);

获取字符串

根据索引获得指定字符 characterAtIndex NSString *str = @"123456"; NSString *str1 = [str characterAtIndex:2] NSLog("str1 = %@",str1);

2.获取字符串的长度 leng

NSString *str = @"123456"; int len = str.length

3.根据索引获得字符串的子串 (1).截取字符串从指定位置开始获得字串 substringFromIndex

NSString *str = @"123456"; NSString *subFormIndex = [str substringFromIndex:3]; //从第三个开始截取 NSLog(@"subFormIndex = %@",subFormIndex);

(2).截取到几个字符串 substringToIndex

NSString *str = @"123456"; NSString *subToIndex = [str substringToIndex:3]; // 截取到第3个 NSLog(@"subToIndex = %@",subToIndex);

(3).截取到几个字符串 substringWithRange

NSString *str = @"123456"; NSString *subRange =[str substringWithRange:NSMakeRange(2, 3)]; // 从第2个开始截取，截取三个 NSLog(@"subRange = %@",subRange);

4.字符串分割 componentsSeparatedByString

NSString *str12 = @"a,b,c,d,e,f"; NSArray *strArray = [str12 componentsSeparatedByString:@","]; for (NSString *str in strArray) { NSLog(@"str = %@",str); }

字符串拼接

NSString *str1 = @"123"; NSString *str2 = @"456" NSString *str = [str1 stringByAppendingString:str2]; NSLog(@"str %@",str);

大小写转换

NSString *str1 = @"aBcDe"; NSString *str2 = [str1 lowercaseString]; NSLog(@"%@",str2); NSString *str3 = [str2 uppercaseString]; NSLog(@"%@",str3);

判断前后缀

1.判断前缀

NSString *str = @"www.imooc.com"; BOOL hasPreFix = [str hasPrefix:@"www."]; if (hasPreFix) { NSLog(@"有前缀"); }else{ NSLog(@"没有前缀"); }

2.判断后缀

NSString *str = @"www.imooc.com"; BOOL hasSufFix = [str hasSuffix:@".com"]; if (hasSufFix) { NSLog(@"有后缀"); }else{ NSLog(@"没有后缀"); }

判断字符是否相等

NSString *str1 = @"Hello"; NSString *str2 = @"Hello"; if ([str1 isEqualToString:str2]) { NSLog(@"Yes"); }else{ NSLog(@"No"); }

查找字符串

NSString *str = @"ab cd ef gh"; // 查找指定字符串的位置 NSRange range1 = [str1 rangeOfString:@"ab"]; NSLog(@"range1.location:%ld, range1.length:%ld",range1.location,range1.length);

字符串替换

1.替换指定范围的字符 stringByReplacingCharactersInRange: withString:

// 替换 NSString *str = @"Hello IOS ,Hello World"; NSString *str1 = [str stringByReplacingCharactersInRange:NSMakeRange(0, 5) withString:@"你好"]; NSLog(@"str1 = %@",str1);

2.替换指定源字符串要被替换的内容的字符 stringByReplacingOccurrencesOfString: withString stringByReplacingOccurrencesOfString -* 源字符串中要被替换的内容*- withString - 替换的字符串

NSString *str = @"Hello IOS ,Hello World"; NSString *str1 =[str stringByReplacingOccurrencesOfString:@"Hello" withString:@"你好"]; NSLog(@"%@",str1);

读取文件

1.读取文件 (1)本地文件

// 读取本地文件 NSString *fileStr = [NSString stringWithContentsOfFile:@"/Users/kev/Desktop/demo.txt" encoding:NSUTF8StringEncoding error:nil]; NSLog(@"file:%@",fileStr);

(1).网络文件

// 读取网络文件 NSString *httpStr = [NSString stringWithContentsOfURL:httpURl encoding:NSUTF8StringEncoding error:nil]; NSLog(@"httpFile:%@",httpStr);

2.写入文件

NSString *str = @"Hello IOS"; BOOL isOk = [str writeToFile:@"/Users/kev/Desktop/demo.txt" atomically:YES encoding:NSUTF8StringEncoding error:nil]; if (isOk) { NSLog(@"YES"); }else{ NSLog(@"NO"); }

NSMutableString

可变字符串是字符串的子类可变字符串可以使用父类的所有方法NSMutableString 不能NSString初始化

添加字符串

NSMutableString *muStr = [[NSMutableString alloc]init]; [muStr setString:@"Hello"];

追加字符串

[muStr appendString:@" World"]; NSLog(@"%@",muStr);

替换字符串

NSRange range2 = [muStr rangeOfString:@"Hello"]; [muStr replaceCharactersInRange:range2 withString:@"IOS"]; NSLog(@"%@",muStr);

插入字符串

[muStr insertString:@"A" atIndex:6]; NSLog(@"%@",muStr);

删除字符串

NSRange rang3 = [muStr rangeOfString:@"IOS"]; [muStr deleteCharactersInRange:rang3]; NSLog(@"%@",muStr);