iOS中网络传输不可避免需要上传，后端需要中文进行escape编码处理后上传。
用NSString中的方法：

[value stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

并不能达到后台服务端的目标。

找到一个与后台服务端契合的方法，与安卓达到一致：

-(NSString *)encodeWithEscape:(NSString *)str
{
    NSArray *hex = [NSArray arrayWithObjects:
                    @"00",@"01",@"02",@"03",@"04",@"05",@"06",@"07",@"08",@"09",@"0A",@"0B",@"0C",@"0D",@"0E",@"0F",
                    @"10",@"11",@"12",@"13",@"14",@"15",@"16",@"17",@"18",@"19",@"1A",@"1B",@"1C",@"1D",@"1E",@"1F",
                    @"20",@"21",@"22",@"23",@"24",@"25",@"26",@"27",@"28",@"29",@"2A",@"2B",@"2C",@"2D",@"2E",@"2F",
                    @"30",@"31",@"32",@"33",@"34",@"35",@"36",@"37",@"38",@"39",@"3A",@"3B",@"3C",@"3D",@"3E",@"3F",
                    @"40",@"41",@"42",@"43",@"44",@"45",@"46",@"47",@"48",@"49",@"4A",@"4B",@"4C",@"4D",@"4E",@"4F",
                    @"50",@"51",@"52",@"53",@"54",@"55",@"56",@"57",@"58",@"59",@"5A",@"5B",@"5C",@"5D",@"5E",@"5F",
                    @"60",@"61",@"62",@"63",@"64",@"65",@"66",@"67",@"68",@"69",@"6A",@"6B",@"6C",@"6D",@"6E",@"6F",
                    @"70",@"71",@"72",@"73",@"74",@"75",@"76",@"77",@"78",@"79",@"7A",@"7B",@"7C",@"7D",@"7E",@"7F",
                    @"80",@"81",@"82",@"83",@"84",@"85",@"86",@"87",@"88",@"89",@"8A",@"8B",@"8C",@"8D",@"8E",@"8F",
                    @"90",@"91",@"92",@"93",@"94",@"95",@"96",@"97",@"98",@"99",@"9A",@"9B",@"9C",@"9D",@"9E",@"9F",
                    @"A0",@"A1",@"A2",@"A3",@"A4",@"A5",@"A6",@"A7",@"A8",@"A9",@"AA",@"AB",@"AC",@"AD",@"AE",@"AF",
                    @"B0",@"B1",@"B2",@"B3",@"B4",@"B5",@"B6",@"B7",@"B8",@"B9",@"BA",@"BB",@"BC",@"BD",@"BE",@"BF",
                    @"C0",@"C1",@"C2",@"C3",@"C4",@"C5",@"C6",@"C7",@"C8",@"C9",@"CA",@"CB",@"CC",@"CD",@"CE",@"CF",
                    @"D0",@"D1",@"D2",@"D3",@"D4",@"D5",@"D6",@"D7",@"D8",@"D9",@"DA",@"DB",@"DC",@"DD",@"DE",@"DF",
                    @"E0",@"E1",@"E2",@"E3",@"E4",@"E5",@"E6",@"E7",@"E8",@"E9",@"EA",@"EB",@"EC",@"ED",@"EE",@"EF",
                    @"F0",@"F1",@"F2",@"F3",@"F4",@"F5",@"F6",@"F7",@"F8",@"F9",@"FA",@"FB",@"FC",@"FD",@"FE",@"FF", nil];

    NSMutableString *result = [NSMutableString stringWithString:@""];
    int strLength = (int)str.length;
    for (int i=0; i<strLength; i++) {
        int ch = [str characterAtIndex:i];
        if (ch == ' ')
        {
            [result appendFormat:@"%c",'+'];
        }
        else if ('A' <= ch && ch <= 'Z')
        {
            [result appendFormat:@"%c",(char)ch];

        }
        else if ('a' <= ch && ch <= 'z')
        {
            [result appendFormat:@"%c",(char)ch];
        }
        else if ('0' <= ch && ch<='9')
        {
            [result appendFormat:@"%c",(char)ch];
        }
        else if (ch == '-' || ch == '_'
                 || ch == '.' || ch == '!'
                 || ch == '~' || ch == '*'
                 || ch == '\'' || ch == '('
                 || ch == ')')
        {
            [result appendFormat:@"%c",(char)ch];
        }
        else if (ch <= 0x007F)
        {
            [result appendFormat:@"%%"];
            [result appendString:[hex objectAtIndex:ch]];
        }
        else
        {
            [result appendFormat:@"%%"];
            [result appendFormat:@"%c",'u'];
            [result appendString:[hex objectAtIndex:ch>>8]];
            [result appendString:[hex objectAtIndex:0x00FF & ch]];
        }
    }
    return result;
}

不知道是否有更简便的方法。