iOS urlstr包含特殊字符转码问题

最近总是忘记给转URL的字符串进行编码，导致链接中包含特殊字符的时候总是出错。
记录下转码方式：

NSString *urlStrEncode = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];

个人理解就是针对URL的组成部分进行编码，个人常用URLQueryAllowedCharacterSet

• URLUserAllowedCharacterSet

返回一个字符集，其中包含URL的用户子组件中允许的字符。

• URLPasswordAllowedCharacterSet

返回一个包含URL密码子组件中允许的字符的字符集。

• URLHostAllowedCharacterSet

返回一个包含URL的宿主子组件中允许的字符的字符集。

• URLPathAllowedCharacterSet

返回一个包含URL路径组件中允许的字符的字符集。';'是一个合法的路径字符，但为了与NSURL最好的兼容，建议使用百分比编码(-stringByAddingPercentEncodingWithAllowedCharacters:如果你传递URLPathAllowedCharacterSet，将百分比编码任何';'字符)。

• URLQueryAllowedCharacterSet

返回一个包含URL查询组件中允许的字符的字符集。

• URLFragmentAllowedCharacterSet

返回包含URL片段组件中允许的字符的字符集。

// Predefined character sets for the six URL components and subcomponents which allow percent encoding. These character sets are passed to -stringByAddingPercentEncodingWithAllowedCharacters:.

// Returns a character set containing the characters allowed in a URL's user subcomponent.
@property (class, readonly, copy) NSCharacterSet *URLUserAllowedCharacterSet API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));

// Returns a character set containing the characters allowed in a URL's password subcomponent.
@property (class, readonly, copy) NSCharacterSet *URLPasswordAllowedCharacterSet API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));

// Returns a character set containing the characters allowed in a URL's host subcomponent.
@property (class, readonly, copy) NSCharacterSet *URLHostAllowedCharacterSet API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));

// Returns a character set containing the characters allowed in a URL's path component. ';' is a legal path character, but it is recommended that it be percent-encoded for best compatibility with NSURL (-stringByAddingPercentEncodingWithAllowedCharacters: will percent-encode any ';' characters if you pass the URLPathAllowedCharacterSet).
@property (class, readonly, copy) NSCharacterSet *URLPathAllowedCharacterSet API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));

// Returns a character set containing the characters allowed in a URL's query component.
@property (class, readonly, copy) NSCharacterSet *URLQueryAllowedCharacterSet API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));

// Returns a character set containing the characters allowed in a URL's fragment component.
@property (class, readonly, copy) NSCharacterSet *URLFragmentAllowedCharacterSet API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));