自定义UIView在addSubview上不可见

Question

I have created a simple ProgressView class that I want to be shown when I'm doing some long tasks. However when I add it to the parent view it never becomes visible and layoutSubviews is never called.

The class is implemented as follows:

@implementation ProgressView

@synthesize title;
@synthesize cancel;
@synthesize progress;
@synthesize delegate;

- (id)initWithFrame:(CGRect)frame
{
    //frame = CGRectMake( 0, 0, 240, 112 );
    self = [super initWithFrame:frame];
    if ( self )
    {
        self.title      = [[UILabel alloc] init];
        self.cancel     = [UIButton buttonWithType: UIButtonTypeCustom];
        self.progress   = [[UIProgressView alloc] init];

        self.backgroundColor    = [UIColor darkGrayColor];

        [self addSubview: self.title];
        [self addSubview: self.cancel];
        [self addSubview: self.progress];
    }
    return self;
}

+ (id) createWithTitle: (NSString*) pTitle
{
    ProgressView* pRet  = [[ProgressView alloc] initWithTitle: pTitle];
    return pRet;
}

- (id) initWithTitle: (NSString*) pTitle
{
    self = [super initWithFrame: CGRectMake( 0, 0, 240, 112 )];
    if ( self )
    {
        self.title.text = pTitle;
    }
    return self;
}

- (void) layoutSubviews
{
    CGSize superFrameSize       = self.superview.frame.size;
    CGSize halfSuperFrameSize   = CGSizeMake( superFrameSize.width / 2, superFrameSize.height / 2 );

    CGSize frameSize            = self.frame.size;
    CGSize halfFrameSize        = CGSizeMake( frameSize.width / 2, frameSize.height / 2 );

    // Center the window on its parent.
    [self setFrame: CGRectMake( halfSuperFrameSize.width - halfFrameSize.width, halfSuperFrameSize.height - halfFrameSize.height, frameSize.width, frameSize.height )];

    [self.title     setFrame: CGRectMake( 4,  4, frameSize.width - 8, 24 )];
    [self.progress  setFrame: CGRectMake( 4, 32, frameSize.width - 8, 24 )];
    [self.cancel    setFrame: CGRectMake( 4, 64, frameSize.width - 8, 44 )];

    [self setNeedsDisplay];
}

And I add the view as follow:

pProgressView   = [[ProgressView alloc] initWithTitle: @"Downloading..."];
[pProgressView setDelegate: self];
[self.view addSubview: pProgressView];

But it never displays. I've checked the remove is definitely happening later and there is plenty of time for the view to become visible. I'm at a loss however. Whatever I do the ProgressView just won't display.

Can someone point out the, most probably stupid, mistake I'm making?

Answer 1

You need to call the designated initializer in -initWithTitle, not [super init]:

self = [self initWithFrame: CGRectMake( 0, 0, 240, 112 )];

The designated initializer is the one which calls the superclass' initializer, see here for more info.

Answer 2

Ok I figured it, and I'm REALLY stupid.

I am using a navigation controller. And the NavigtionViewController handles the download initiation. Only problem is that its being generated by a child view controller. So I'm adding my ProgressView to a view that is currently not visible ...

D'OH!

Sorry all.

My new addSubview code is as follows:

[self.navigationController.topViewController.view addSubview: pProgressView];