其实还完全没有入门。。先把知道的整上来把，以后一点一点加

-(BOOL)CheckInput:(NSString *)_text

{

    NSString *Regex = @"[0]\\.\\d+(\\,[0]\\.\\d+)*";

    NSPredicate *emailTest = [NSPredicatepredicateWithFormat:@"SELF MATCHES %@", Regex];

    return [emailTest evaluateWithObject:_text];

}

myText是个textField

        if([myText.textrangeOfString:@","].location != NSNotFound)

        {

            red=[[myText.textsubstringToIndex:[myText.textrangeOfString:@","].location] floatValue];

            myTextTest.text=[NSStringstringWithFormat:@"start:_%f_end",red];

        }