iOS URL编码

1、原始方法：stringByAddingPercentEscapesUsingEncoding: ios(2.0,9.0)

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NSString *data = @"https://baike.baidu.com/item/百度百科/85895?fr=aladdin";
NSString *urlStr = [data stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSLog(@"%@", urlStr);

结果输出：

https://baike.baidu.com/item/%E7%99%BE%E5%BA%A6%E7%99%BE%E7%A7%91/85895?fr=aladdin

2、新方法：stringByAddingPercentEncodingWithAllowedCharacters: ios(7.0)

NSString *data = @"https://baike.baidu.com/item/百度百科/85895?fr=aladdin";

// 以下两句代码处理结果一样：对`#%^{}[]|\"<>空格 这些字符进行编码
NSString *dataUTF8 = [data stringByAddingPercentEncodingWithAllowedCharacters:[[NSCharacterSet characterSetWithCharactersInString:@"`#%^{}[]|\"<> "] invertedSet]];
// NSString *dataUTF8 = [data stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];  

NSLog(@"%@",dataUTF8);

结果输出：

https://baike.baidu.com/item/%E7%99%BE%E5%BA%A6%E7%99%BE%E7%A7%91/85895?fr=aladdin

NSCharacterSet (NSURLUtilities)

URLFragmentAllowedCharacterSet  "#%<>[\]^`{|}
URLHostAllowedCharacterSet      "#%/<>?@\^`{|}
URLPasswordAllowedCharacterSet  "#%/:<>?@[\]^`{|}
URLPathAllowedCharacterSet      "#%;<>?[\]^`{|}
URLQueryAllowedCharacterSet    "#%<>[\]^`{|}
URLUserAllowedCharacterSet      "#%/:<>?@[\]^`

但是现在有的URL中包含的#是不需要进行编码的，可以修改代码为：

// 字符集中若哪个字符不需要编码，去掉即可
NSString *dataUTF8 = [data stringByAddingPercentEncodingWithAllowedCharacters:[[NSCharacterSet characterSetWithCharactersInString:@"`%^{}[]|\"<> "] invertedSet]]; 

参考资料：
url出现特殊字符处理