I defer to your technical knowledge, but I think one should do related initializations in one place, and that isn't the place I would choose.
Yet, it does solve the OP's problem at no cost, making it a puzzle rather than a problem. Why isn't it appearing as expected? David On Mar 20, 2013, at 10:55 AM, Matt Neuburg <m...@tidbits.com> wrote: > Far be it from me to step into a controversy (ha ha), but I feel compelled to > push back against this oversimplification. > > (1) It's true that viewWillAppear can occur multiple times, but that doesn't > make it a bad place to do one-time initialization. It is easy to distinguish > the *first* time from all the other times, so the "once" problem is not > really a problem at all. > > (2) viewDidLoad can also occur multiple times - well, it could before iOS 6. > So that's no solution, per se, to the "once" problem. > > (3) For many things, viewWillAppear is much better place to initialize than > viewDidLoad. Remember, viewDidLoad doesn't mean the view has been placed into > the interface yet. It just means that the view controller has a view - no > more. So, for example, dimensions may not yet be correct. > > (4) The tendency to fall back on viewDidLoad mindlessly can be wrong for > other reasons. As I point out in my book, Apple warns (in the > UIViewController class reference, under navigationItem) that configuring a > view controller's navigation item in conjunction with the creation of its > view is not a good idea, because the circumstances under which the view is > needed are not identical to the circumstances under which the navigation item > is needed. (However, Apple's own code examples then proceed to violate this > warning quite shamelessly.) > > m. > > > On Tue, 19 Mar 2013 20:28:29 -0700, David Rowland <rowla...@sbcglobal.net> > said: >> viewWillAppear occurs every time the view reappears, which may be frequently >> and has nothing to do with the creation and initialization of the view. Each >> time it appears you are recreating the button and setting in >> self.prevButton, e.g. which will release the former button and install an >> identical one. So, no, this is not the recommended place to do this. >> >> Why viewDidLoad fails isn't clear. Is it possible that the toolbar is hidden >> or behind some other view? >> >> >> On Mar 19, 2013, at 6:48 PM, Koen van der Drift <koenvanderdr...@gmail.com> >> wrote: >> >>> I am programmatically adding some toolbar items to a view in a >>> UIViewController subclass, and it only seems to work when I put the code in >>> viewWillAppear: >>> >>> // add a toolbar with a prev and next button >>> self.navigationController.toolbarHidden = NO; >>> UIBarButtonItem *flexibleItem = [[UIBarButtonItem alloc] >>> initWithBarButtonSystemItem: UIBarButtonSystemItemFlexibleSpace target: >>> self action: nil]; >>> self.prevButton = [[UIBarButtonItem alloc] initWithTitle: @"Prev" style: >>> UIBarButtonItemStyleBordered target: self action: nil]; >>> self.nextButton = [[UIBarButtonItem alloc] initWithTitle: @"Next" style: >>> UIBarButtonItemStyleBordered target: self action: nil]; >>> >>> self.toolbarItems = [NSArray arrayWithObjects: self.prevButton, >>> flexibleItem, self.nextButton, nil]; >>> >>> If I put it in viewDidLoad, the toolbar never shows up. In the book by >>> Conway and Hillegass (3rd ed), they put similar code in init, but that also >>> doesn't work in my case. Interestingly, I am adding a UISearchBar in init, >>> and that works just fine. >>> >>> Why is that? Is viewWillAppear the recommended place to do this? >>> > > -- > matt neuburg, phd = m...@tidbits.com, <http://www.apeth.net/matt/> > A fool + a tool + an autorelease pool = cool! > Programming iOS 6! http://shop.oreilly.com/product/0636920029717.do _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
