OC中NSString 的方法

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));

//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);

//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);