NSString* string1 = @"https://www.cloudsafe.com/文件夹";

NSString* string2 = [string1 stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString* string3 = [string2 stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString* string4 = [string2 stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString* string5 = [string3 stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString* string6 = [string4 stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

NSString* string7 = [string5 stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

输出结果: string5 &  重复编码encode

string1:https://www.cloudsafe.com/文件夹

string2:https://www.cloudsafe.com/%E6%96%87%E4%BB%B6%E5%A4%B9

string3:https://www.cloudsafe.com/%25E6%2596%2587%25E4%25BB%25B6%25E5%25A4%25B9

string4:https://www.cloudsafe.com/文件夹

string5:https://www.cloudsafe.com/%E6%96%87%E4%BB%B6%E5%A4%B9

string6:https://www.cloudsafe.com/文件夹

string7:https://www.cloudsafe.com/文件夹

-(NSString *)UrlEncodedString:(NSString * )sourceText

{

    NSString *result = (NSString *)CFBridgingRelease(CFURLCreateStringByAddingPercentEscapes(kCFAllocatorDefault,(CFStringRef)sourceText ,NULL ,CFSTR("!*'();:@&=+$,/?%#[]") ,kCFStringEncodingUTF8));

    return result;

}