【iOS开发系列】escape编码

+(NSString *)escape:(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 = 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;
}