[论坛提问] NSString中常用的一些方法

<pre code_snippet_id="332750" snippet_file_name="blog_20140507_1_899224" name="code" class="html"> NSString *str1 = @"BeiJing";
NSString *str2 = @"beijing";

//全部转为大写
NSLog(@"%@",[str1 uppercaseString]);
//全部转为小写
NSLog(@"%@",[str1 lowercaseString]);

//首字母大写
NSLog(@"%@",[str1 capitalizedString]);

//比较两个字符串内容是否相同
BOOL b =[str1 isEqualToString:str2];

//两个字符串内容比较
//NSOrderedAscending 右边 > 左边
//NSOrderedSame       内容相同
//NSOrderedDescending 左边 > 右边
NSComparisonResult result = [str1 compare:str2];
if (result == NSOrderedAscending) {
      NSLog(@"右边 > 左边");
}else if(result == NSOrderedSame){
      NSLog(@"内容相同");
}else if (result == NSOrderedDescending){
      NSLog(@"左边 > 右边");
}

//忽略大小写进行比较，返回值与compare一样
result = [str1 caseInsensitiveCompare:str2];
if (result == NSOrderedAscending) {
      NSLog(@"右边 > 左边");
}else if(result == NSOrderedSame){
      NSLog(@"内容相同");
}else if (result == NSOrderedDescending){
      NSLog(@"左边 > 右边");
}

//判断字符串是否以指定字符串开头
[str1 hasPrefix:@"aaa"];
//判断字符串是否以指定字符串结尾
[str1 hasSuffix:@"aaa"];

//判断字符串是否包含指定字符串，返回位置和长度
NSRange range = [@"123456" rangeOfString:@"456"];
NSLog(@"%@", NSStringFromRange(range));

//反向搜索
range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch];
NSLog(@"%@",NSStringFromRange(range));

//指定范围进行搜索
range = NSMakeRange(0, 9);
range = [@"123456456qweasasd456" rangeOfString:@"456" options:NSBackwardsSearch range:range];
NSLog(@"%@",NSStringFromRange(range));</pre>
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<pre code_snippet_id="332750" snippet_file_name="blog_20140507_2_3625630" name="code" class="cpp" style="display: none;">//字符串的截取
      NSString *str = @"123456789";
      NSLog(@"%@",[str substringFromIndex:3]);
      NSLog(@"%@",[str substringToIndex:6]);
      NSLog(@"%@",[str substringWithRange:NSMakeRange(3, 3)]);

      //用指定字符串分割字符串，返回一个数组
      NSArray *array = [@"1,2,3,4,5,6" componentsSeparatedByString:@","];
      NSLog(@"%@",array);

      //将数组中的字符串组合成一个文件路径
      NSMutableArray *components = [NSMutableArray array];
      [components addObject:@"Users"];
      [components addObject:@"CentralPerk"];
      [components addObject:@"Desktop"];
      NSString *path = [NSString pathWithComponents:components];
      NSLog(@"%@",path);  //Users/CentralPerk/Desktop

      //将一个路径分割成一个数组
      NSArray *array1 = [path pathComponents];
      NSLog(@"%@",array1);

      //判断是否为绝对路径(依据：是否以'/'开始)
      path = @"/Users/CentralPerk/Desktop";
      NSLog(@"%i",[path isAbsolutePath]);

      //获取最后一个目录
      NSLog(@"%@",[path lastPathComponent]);

      //删除最后一个目录
      NSLog(@"%@",[path stringByDeletingLastPathComponent]);

      //拼接一个目录
      NSLog(@"%@",[path stringByAppendingPathComponent:@"aaa"]); ///Users/CentralPerk/Desktop/aaa
      NSLog(@"%@",[path stringByAppendingString:@"aaa"]);    ///Users/CentralPerk/Desktopaaa
      NSLog(@"%@",[path stringByAppendingFormat:@"%@%@",@"b",@"c"]);  ///Users/CentralPerk/Desktopbc

      //拓展名出来
      //获取拓展名,不带.
      NSString *str2 = @"Users/CentralPerk/Desktop/test.txt";
      NSLog(@"%@",[str2 pathExtension]);
      //添加拓展名,不需要带.
      NSLog(@"%@",[str2 stringByAppendingPathExtension:@"mp3"]);
      //删除拓展名,带.一块删除
      NSLog(@"%@",[str2 stringByDeletingPathExtension]);

      //字符串转为 int double float
      NSString *str3 = @"123";
      NSLog(@"%i",[str3 intValue]);
      NSLog(@"%zi",[str3 length]);

      //取出指定位置的字符
      unichar c = [str3 characterAtIndex:2];
      NSLog(@"%c",c);

      //转为C语言的字符串
      const char *s = [str3 UTF8String];
      NSLog(@"%s",s);
</pre>
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[论坛提问] NSString中常用的一些方法

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