UIView仅在第二次调用后显示

Question

I have a view controller that is calling a custom UIView via an IBAction.The custom view contains a UIPickerView that slides up from the bottom of the screen and a toolbar with 'cancel' and 'done' buttons above it. The problem is that the view only appears on the screen after being called for the second time . Using breakpoints I can verify that every single line of code is being called both times. Everything seems to be happening the same way each time. Nothing is NIL, and in fact it's like this for the duration that the app is running, not only the first time it's called. You always have to click the button twice to get the view to appear for as long as the app is running.

Admittedly, the code for the custom picker view is not mine. I copied it from someone else's example. I'm not sure if it's the problem or not. I don't see how it could be, but I'm a bit over my head here. This is how I'm calling the view from my view controller.

- (IBAction)statusPickerButtonPressed:(id)sender {

self.scrollPickerView = [[StatusPickerView alloc]init];

[self.navigationController.view addSubview:self.scrollPickerView];
self.scrollPickerView.delegate = self;
self.scrollPickerView.dataSource = self;
}

and here's the custom UIView

#import "StatusPickerView.h"

@interface StatusPickerView ()
@property NSArray *pickerArray;
@property NSInteger selectedRow;
@end

@implementation StatusPickerView


- (id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if (self) {
    [self setToolbar];
    [self becomeFirstResponder];


    float screenWidth = [UIScreen mainScreen].bounds.size.width;
    float pickerWidth = screenWidth * 3 / 4;
    float xPoint = screenWidth / 2 - pickerWidth / 2;



    [self setFrame: CGRectMake(xPoint, 50.0f, pickerWidth, 180.0f)];
    self.showsSelectionIndicator = YES;
    [self selectRow:3 inComponent:0 animated:YES];


}
return self;

}


-(void)setToolbar
{
_toolbar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
[_toolbar setBarStyle:UIBarStyleDefault];

UIBarButtonItem * btnCancel = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCancel
                                                                            target:self action:@selector(barbtnPressed:)];
UIBarButtonItem * flexible = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                                                                          target:nil action:nil];
UIBarButtonItem * btnDone = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone
                                                                          target:self action:@selector(barbtnPressed:)];
[btnCancel setTag:1];
[btnCancel setStyle:UIBarButtonItemStyleBordered];

[btnDone setTag:2];
[btnDone setStyle:UIBarButtonItemStyleBordered];

NSArray * btnArray = [[NSArray alloc] initWithObjects:btnCancel, flexible, btnDone, nil];
[_toolbar setItems:btnArray];

self.inputAccessoryView = _toolbar;
self.inputView = self;
}

-(BOOL)canBecomeFirstResponder
{
return true;
}




-(void)barbtnPressed:(id)sender
{
NSInteger tag = [sender tag];
switch (tag) {
    case 1:
    {
        [self removeFromSuperview];
        break;
    }
    case 2:{
        [self removeFromSuperview];
        self.selectedRow = [self selectedRowInComponent:0];
        [[NSNotificationCenter defaultCenter]postNotificationName:@"user_selected_new_section" object:self];

    }
    default:
        break;
}
}

-(int)giveSelectedRow{

return self.selectedRow; 
}

I'm fully prepared to feel foolish here, as the solution is probably obvious, just not obvious to myself.

edit: I tried using [self.view.window addSubview:self.scrollPickerView]; instead of [self.navigationController.view addSubview:self.scrollPickerView]; , and the behavior is exactly the same.

Answer 1

This line:

 [self.navigationController.view addSubview:self.scrollPickerView];

should read:

 [self.view addSubview:self.scrollPickerView];

Answer 2

You're calling -init instead of -initWithFrame: , so your view is ending up with the default frame of CGRectZero . Considering that you're then making a frame of your own, that call might as well pass that in to start out with:

self.scrollPickerView = [[ScrollPickerView alloc] initWithFrame:CGRectZero];

Alternatively, you could keep the current self.scrollPickerView = … code and change the -initWithFrame: to an -init , like this:

- (id)init
{
    float screenWidth = [UIScreen mainScreen].bounds.size.width;
    float pickerWidth = screenWidth * 3 / 4;
    float xPoint = screenWidth / 2 - pickerWidth / 2;
    self = [super initWithFrame:CGRectMake(xPoint, 50.0f, pickerWidth, 180.0f)];

    if (self) {
        [self setToolbar];
        [self becomeFirstResponder];

        self.showsSelectionIndicator = YES;
        [self selectRow:3 inComponent:0 animated:YES];
    }
    return self;
}