如何初始化从xib加载的UIView子类？ 继承问题

Question

Hi I created UIView subclass MightyPickerView that is loaded from xib like this.

- (instancetype)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];

  if (self) {
    NSArray *arrayOfViews = [[NSBundle mainBundle] loadNibNamed:@"MightyPickerView" owner:self options:nil];

    if ([arrayOfViews count] < 1) {
      return nil;
    }
    if (![[arrayOfViews objectAtIndex:0] isKindOfClass:[MightyPickerView class]]) {
      return nil;
    }
    self = [arrayOfViews objectAtIndex:0];
  }
  return self;
}

Until now this works great also I used this in many previous projects without any issues. But now I want to create MightyPickerView's subclass called TimePickerView .

- (instancetype)initWithFrame:(CGRect)frame
{
  self = [super initWithFrame:frame]; // here's the problem
  if (self) {
    [self setupSizes];
  }
  return self;
}

When I run the app it crashes

[MightyPickerView setupSizes]: unrecognized selector sent to instance 0x137e53660

The problem is that this line self = [super initWithFrame:frame]; return MightyPickerView instead of TimePickerView.

How should I write the MightyPickerView's initializor so that it will return subclass if it needs to.

Answer 1

What you're doing makes no sense. You should not be misusing initWithFrame to have your view turn around and load itself from a nib. If you want to load a MightyPickerView from a nib, load it from a nib, ie have some other class say [[NSBundle mainBundle] loadNibNamed:@"MightyPickerView" owner:nil options:nil]; and pull out the view. To encapsulate, use a class factory method, maybe. Do not do this sort of skanky self-substitution inside an init . It may have been apparently working but it was always wrong behavior and now it has come back to bite you.