iOS 9以後Url連接的NSUTF8StringEncoding轉碼實現

在iOS中經過WebView加載Url或者請求HTTP時，如果連接中包含中文、特殊符號&％或是空格等都須要預先進行一下轉碼纔可正常訪問。

許久沒編碼，原先的方法已廢棄了都，在此對應當前最新的方法進行記錄：

 

官方源碼「NSRUL.h」文件中能夠看到以下信息：後兩個方法已廢棄，從iOS7.0開始提供新的兩個方法：

@interface NSString (NSURLUtilities)

// Returns a new string made from the receiver by replacing all characters not in the allowedCharacters set with percent encoded characters. UTF-8 encoding is used to determine the correct percent encoded characters. Entire URL strings cannot be percent-encoded. This method is intended to percent-encode an URL component or subcomponent string, NOT the entire URL string. Any characters in allowedCharacters outside of the 7-bit ASCII range are ignored.
- (nullable NSString *)stringByAddingPercentEncodingWithAllowedCharacters:(NSCharacterSet *)allowedCharacters API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));

// Returns a new string made from the receiver by replacing all percent encoded sequences with the matching UTF-8 characters.
@property (nullable, readonly, copy) NSString *stringByRemovingPercentEncoding API_AVAILABLE(macos(10.9), ios(7.0), watchos(2.0), tvos(9.0));


- (nullable NSString *)stringByAddingPercentEscapesUsingEncoding:(NSStringEncoding)enc API_DEPRECATED("Use -stringByAddingPercentEncodingWithAllowedCharacters: instead, which always uses the recommended UTF-8 encoding, and which encodes for a specific URL component or subcomponent since each URL component or subcomponent has different rules for what characters are valid.", macos(10.0,10.11), ios(2.0,9.0), watchos(2.0,2.0), tvos(9.0,9.0));
- (nullable NSString *)stringByReplacingPercentEscapesUsingEncoding:(NSStringEncoding)enc API_DEPRECATED("Use -stringByRemovingPercentEncoding instead, which always uses the recommended UTF-8 encoding.", macos(10.0,10.11), ios(2.0,9.0), watchos(2.0,2.0), tvos(9.0,9.0));

@end

 

一：stringByAddingPercentEncodingWithAllowedCharacters方法：是將普通字符轉爲百分比編碼字符；

調用方法以下：

NSString *originalString = @"浙江省";
    
NSString *charactersToEscape = @"?!@#$^&%*+,:;='\"`<>()[]{}/\\| ";
NSCharacterSet *allowedCharacters = [[NSCharacterSet characterSetWithCharactersInString:charactersToEscape] invertedSet];
NSString *encodeString = [originalString stringByAddingPercentEncodingWithAllowedCharacters:allowedCharacters];

eg. 「浙江省」轉碼後即變成了「%E6%B5%99%E6%B1%9F%E7%9C%81」；

 

方法二：stringByRemovingPercentEncoding方法：則是將百分比編碼字符從新轉會普通字符；

調用方法以下：

NSString *decodeString = [encodeString stringByRemovingPercentEncoding];