ios中对url中得特殊字符处理

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