iOS macOS URL编码和解码过程（UrlEncode）

字符串URL编码实现

NSString *urlStr = @"你好0123456789abcxyzABCXYZ-_.~&!*'();:@&=+$,/?#[]% ";
//方式一编码对比
NSString *encodingString = [urlStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSLog(@"url编码1-1 = %@",encodingString);
 
//方式二自定义字符集 ABC-_~.!*'();:@&=+ $,/?%#[]  编码对比
NSString *encodeStr2 = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)urlStr, NULL, (CFStringRef)@"ABC-_~.!*'();:=+ $,/?%#[]", kCFStringEncodingUTF8));
    NSLog(@"url编码2-2 = %@",encodeStr2);
 
//系统提供的枚举字符集，这些字符不需要  编译
NSString *encodeStr3 = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:[NSCharacterSet URLQueryAllowedCharacterSet]];
NSLog(@"url编码3-1 = %@",encodeStr3);
    
//自定义字符不需要编译的字符集，为空字符集，将所有字符用百分号编码
NSCharacterSet *characterSet = [NSCharacterSet characterSetWithCharactersInString:@""];
NSString *encodeStr4 = [urlStr stringByAddingPercentEncodingWithAllowedCharacters:characterSet];
    NSLog(@"url编码3-2 = %@",encodeStr4);

打印结果是:

网上常见的字符集枚举说明（供参考）:

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

字符串URL解码实现

//上段代码的结果为encodeStr3入参
NSString *decodedStr3 = [encodeStr3 stringByRemovingPercentEncoding];
NSLog(@"url编码3-1 = %@",decodedStr3);
//上段代码的结果为encodeStr4入参
NSString *decodedStr4 = [encodeStr4 stringByRemovingPercentEncoding];
    NSLog(@"url编码3-2 = %@",decodedStr4);

打印结果是