iOS textfield输入的是金额，逻辑判断

输入金额的需求
在UITextField中输入金额，我们需要判断输入金额的有效性，比如小数点后不能超过两位、金额需要大于等于1分、小数点只能出现一个等等,下面我就贴一下自己写的一个判断，希望可以帮助初学者

首先你需要让textfield遵循<UITextFieldDelegate>
在- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string;方法中实现我们的判断

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    //限制只能输入数字
    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];//当前输入的字符
        if ((single >= '0' && single <= '9') || single == '.') {
            //数据格式正确
            if([textField.text length] == 0){
                if(single == '.') {
                    [MBProgressHUD showError:@"请输入正确的价格"];
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }
            
            //输入的字符是否是小数点
            if (single == '.') {
                if(!isHaveDian) {
                    //text中还没有小数点
                    isHaveDian = YES;
                    return YES;
                    
                }else{
                    [MBProgressHUD showError:@"请输入正确的价格"];
                    [textField.text stringByReplacingCharactersInRange:range withString:@""];
                    return NO;
                }
            }else{
                //存在小数点
                if (isHaveDian) {
                    
                    //判断小数点的位数
                    NSRange ran = [textField.text rangeOfString:@"."];
                    if (range.location - ran.location <= 2) {
                        return YES;
                    }else{
                        [MBProgressHUD showError:@"请输入正确的价格"];
                        return NO;
                    }
                }else{
                    return YES;
                }
            }
        }else{
            //输入的数据格式不正确
            [MBProgressHUD showError:@"请输入正确的价格"];
            [textField.text stringByReplacingCharactersInRange:range withString:@""];
            return NO;
        }
    }  
    else  
    {  
        return YES;  
    }  
}
希望简单的几句判断能帮助到您