[iOS]URL的编码与解码

URL的编码与解码

转入地址：https://www.jianshu.com/p/4bc22614148e
新建NSString的分类，对URL进行编码与解码

@interface NSString (URLEncoding)

- (NSString *)URLEncodedString;
- (NSString *)URLDecodedString;

@end

@implementation NSString (URLEncoding)
/*
CFURLCreateStringByAddingPercentEscapes(<#CFAllocatorRef allocator#>, <#CFStringRef originalString#>, <#CFStringRef charactersToLeaveEscaped#>)—Core Foundation 框架提供的C函数，把内容转为URL编码
<#CFStringRef originalString#> — 制定了将本身为非法URL字符不进行编码的字符集合，例如:"! * ()"等符号
<#CFStringRef charactersToLeaveEscaped#> — 将本身为合法的URL字符需要进行编码的字符集合
*/
- (NSString *)URLEncodedString { 
    NSString *encodedString = (NSString *) CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault, (CFStringRef)unencodedString, NULL, (CFStringRef)@"!*'();:@&=+$,/?%#[]", kCFStringEncodingUTF8)); 
    return encodedString; 
}

/* 
CFURLCreateStringByReplacingPercentEscapes(<#CFAllocatorRef allocator#>, <#CFStringRef originalString#>, <#CFStringRef charactersToLeaveEscaped#>)
<#CFStringRef charactersToLeaveEscaped#> — 指定不进行编码的字符集合 
*/ 
- (NSString *)URLDecodedString { 
    NSString *decodedString = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL, (__bridge CFStringRef)encodedString, CFSTR(""), CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding)); 
    return decodedString; 
}

@end