NSString的几个方法（rangeOfString，hasPrefix，hasSuffix，改变大小写...）

- (NSRange)rangeOfString:(NSString *)searchString;//查找字符串中是包涵在某个字符串，并返回其开始位置和长度

例：

NSRange range = [link rangeOfString:@"target=_blank"];

if(range.location != NSNotFound)

{

[[UIApplication sharedApplication] openURL:[NSURL URLWithString:link]];

}

-(BOOL) hasPrefix:(NSString *) //astring;检查字符串是否以astring开头；

-(BOOL) hasSuffix:(NSString *) //astring;检查字符串是否以astring结尾；

1.) lowercaseString: 将字符串转换为小写
2.) uppercaseString: 将字符串转换为大写

3.) capitalizedString:将字符串的首字母大写

忽略大小写比较

//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");
   } 

//拓展名
        //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