Question

我是新手使用块语法并面临以下问题。下面的代码调用导致问题的类的另一个静态方法。通过点击栏上的下一个按钮调用下面的代码。这段代码的语法有什么错误吗？

-(BOOL) shouldPerformSegueWithIdentifier:(NSString *)identifier sender:(id)sender
    {
        if (![sender isKindOfClass:[UIBarButtonItem class] ]) {
            return true;
        }
        // Trim the spaces
        self.stewardsNameTextField.text = [self.stewardsNameTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet] ];

    self.trackNameTextField.text = [self.trackNameTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet] ];

    self.curatorNameTextField.text = [self.curatorNameTextField.text stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet] ];


    bool isValid =[JLTValidator validateFields: @[self.stewardsNameTextField, self.trackNameTextField, self.curatorNameTextField, self.weatherConditionSegment, self.trackConditionSegment] withScrollToCallback: ^(UIView * invalidField) // problem is here. Is this incorrect syntax?
            {
                if (invalidField == self.stewardsNameTextField || invalidField == self.trackNameTextField || invalidField == self.curatorNameTextField)
                {
                    [invalidField becomeFirstResponder];
                }
                else
                {
                    UIEdgeInsets contentInsets = UIEdgeInsetsZero;
                    CGPoint top = CGPointMake(0, invalidField.frame.origin.y - 90);

                    [_scrollView setContentOffset:top animated:YES];
                    _scrollView.scrollIndicatorInsets=contentInsets;
                }

                if (!isValid) {
                    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sorry!" message:@"Please fill out the marked fields." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
                    [alert show];
                }

                return isValid;
            }];

}

调用类的静态方法的定义：

+(BOOL)validateFields:(NSArray *)fields
    {
        return [JLTValidator validateFields:fields withScrollToCallback:nil];
    }
    +(BOOL)validateFields:(NSArray *)fields andShouldDisplayMessage : (bool) shouldDisplayMessage
    {
        return [JLTValidator validateFields:fields withScrollToCallback:nil andShouldDisplayMessage:shouldDisplayMessage];
    }

+(BOOL)validateFields:(NSArray *)fields withScrollToCallback : (void (^) (UIView *))scrollToCallback
{
    return [JLTValidator validateFields:fields withScrollToCallback:scrollToCallback andShouldDisplayMessage:true];
}

+(BOOL)validateFields:(NSArray *)fields withScrollToCallback : (void (^) (UIView *))scrollToCallback andShouldDisplayMessage : (bool) shouldDisplayMessage
{

}

这里有什么不对？请指导。

Answer 1

+(BOOL)validateFields:(NSArray *)fields withScrollToCallback : (void (^) (UIView *))scrollToCallback

此方法中的block参数不返回任何内容（您可以在那里看到'void'）。因此，如果在块内，则返回BOOL值（isValid）不正确。而且，你返回了你想要得到的值（isValid = ..... isValid），这也是一个错误。

我不知道你在街区内尝试了什么，但为了解决这个问题，你可以这样做：

bool isValid =[JLTValidator validateFields: @[self.stewardsNameTextField, self.trackNameTextField, self.curatorNameTextField, self.weatherConditionSegment, self.trackConditionSegment] withScrollToCallback: ^(UIView * invalidField) // problem is here. Is this incorrect syntax?
        {
            if (invalidField == self.stewardsNameTextField || invalidField == self.trackNameTextField || invalidField == self.curatorNameTextField)
            {
                [invalidField becomeFirstResponder];
            }
            else
            {
                UIEdgeInsets contentInsets = UIEdgeInsetsZero;
                CGPoint top = CGPointMake(0, invalidField.frame.origin.y - 90);

                [_scrollView setContentOffset:top animated:YES];
                _scrollView.scrollIndicatorInsets=contentInsets;
            }
        }];

if (!isValid) {
    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Sorry!" message:@"Please fill out the marked fields." delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
    [alert show];
}

使用块时，没有已知的选择器类方法

1 个答案: