Open Radar

 
Summary:
When implementing the method -pickerView:rowHeightForComponent in a UIPickerViewDelegate, the method is called more times than there are components in the PickerView.

Steps to Reproduce:
1. Use Xcode Version 5.0.1 (5A2053) on Mac OS X 10.9, build 13A603
2. Create empty application.
3. Add new UIViewController subclass with .xib, add PickerView to .xib.

4. In the AppDelegate:
4a. Create UIViewController subclass
4b. Create UINavigationController, initWithRootViewController using above subclass.
4c. Set window.rootViewController to the UINavigationController.

5. In the UIViewController subclass:
5a. Implement the UIPickerViewDataSource Protocol methods -numberOfComponentsInPickerView: & -pickerView:numberOfRowsInComponent:.  Return 1 for numberOfComponents.
5b. Implement the UIPickerViewDelegate Protocol methods -pickerView:titleForRow:forComponent:, -pickerView:rowHeightForComponent: & -pickerView:widthForComponent:.
5c. In the methods in 5a & 5b that require component number as input, add NSParameterAssert(component == 0).

6. Run the app in Xcode.

Expected Results:
I expected that the app would launch normally and I would be able to manipulate the picker view.

Actual Results:
The app launches, but then generates an assertion failure in pickerView:rowHeightForComponent: when this method is called with a component of 1.  This should not happen as the picker view is defined to only have one component by the data source implementation.

Version:
iOS 7.0

Notes:
This problem always occurs, however:
1.  Remove the NSParameterAssert from pickerView:rowHeightForComponent, and the app seems to launch normally.  Supplying a row height for a non-existant component seems to be a no-op.
2.  Remove pickerView:rowHeightForComponent from the delegate implementation, and the app seems to launch normally.  Did not track component number in this case.

Also, attached is a sample project/app to illustrate the problem.

Configuration:
Always occurs when the UIPickerViewDataDelegate method -pickerView:rowHeightForComponent is implemented.

Attachments:
'Sample App.zip' was successfully uploaded.