更改 NSURL

Question

我尝试在 NSURL 中插入一些内容。我从 json 字符串获取 URL：

imageUrl = [NSURL URLWithString:[[jsonPost objectAtIndex:countPage] objectForKey:@"excerpt"]];

imageURL 现在包含以下内容：

http://www.site.com/images/uploads/2011/04/2010-12-14-image.gif

我试图实现的是将 URL 更改为：

http://www.site.com/images/uploads/2011/04/2010-12-14-image_r.gif

因此，在扩展名之前将添加 _r 。

Answer 1

方法 1：（如果您知道文件扩展名是 .gif，则可以正常工作）

NSString *string = [[jsonPost objectAtIndex:countPage] objectForKey:@"excerpt"]];
NSArray *array = [string componentsSeparatedByString:@".gif"]; //separated by dot
NSString *editedString = [NSString stringWithFormat:@"%@_r.gif",[array objectAtIndex:0]];
NSURL *url = [NSURL urlWithString:editedString];

编辑：
更可靠的解决方案：

NSRange range;
range.location = 0;//starting from the first character
range.length = string.length - 4;//excluding the last 4 characters
//of course you have to make sure the .extension part is 4 characters long(at least fixed length), not like .torrent or .rmvb
NSString *newString = [urlString substringWithRange:range];//this should give you the url part without the file extension

//then append the newString with something and make your url with this string