iOS開發之UITextField(輸入框)限制只能輸入整數和小數

我的是限制小數點後8位

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{     //    限制只能輸入數字
    BOOL isHaveDian = YES;
    if ([string isEqualToString:@" "]) {
        return NO;
    }
    if ([textField.text rangeOfString:@"."].location == NSNotFound) {
        isHaveDian = NO;
    }
    if ([string length] > 0) {
        
        unichar single = [string characterAtIndex:0];//當前輸入的字元
        if ((single >= '0' && single <= '9') || single == '.') {//資料格式正確
            
            if([textField.text length] == 0){
                if(single == '.') {
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }
            //輸入的字元是否是小數點
            if (single == '.') {
                if(!isHaveDian)//text中還沒有小數點
                {
                    isHaveDian = YES;
                    return YES;
                    
                }else{
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }else{
                if (isHaveDian) {//存在小數點
                    
                    //判斷小數點的位元
                    NSRange ran = [textField.text rangeOfString:@"."];
                    if (range.location - ran.location <= 8) {
                        return YES;
                    }else{
                        return NO;
                    }
                }else{
                    return YES;
                }
            }
        }else{//輸入的資料格式不正確
            [textField.text stringByReplacingCharactersInRange:range withString:@""];
            return NO;
        }
    }
    else
    {
        return YES;
    }
}