Now,I gonna Develop an App ,which wants to switch from many different Views irregularly,also the views need to load large resources,AKA,it's hard to manage memory.Are there any good solustion?
PS：I created a ViewController as RootViewController,and When a button was Touch,run the code as
"ViewController=newController"
.The problem came,The new View loaded wrong way,it rotate so that couldn't show in a correct way.
I google for the solution,some one said ,I should replace the rootViewController,just like that,
[UIApplication sharedApplication].delegate.window.rootViewController=newController;
But I can't get/set the rootViewController in other class though it's a singleton.
Why not having a class that handles all the view switches ?
This article describes an architecture that might be helpfull: http://www.mikeziray.com/2010/01/27/handling-your-initial-view-controllers-for-iphone/comment-page-1/#comment-607
I'm trying to find a method thats called once everything has been loaded and displayed. The reason I want to do this is because I have some images that take some time to load in so instead of showing them a black screen I want to show a loading page and then call a setup method.
However the only methods I can find are called before the views come into view...
I am probably being really dumb..
Any help would be great.
Disco
You can use
- (void)viewWillLoad;
and
- (void)viewDidAppear:(BOOL)animated;
to do what you need.
How about
- (void)viewDidAppear:(BOOL)animated;
When I use the TTLauncher to call a TTTableViewController the table is loaded correctly it shows the "Loading..." screen as expected and then the table:
- (void)launcherView:(TTLauncherView*)launcher didSelectItem:(TTLauncherItem*)item {
[[TTNavigator navigator] openURLAction:[TTURLAction actionWithURLPath:item.URL]];
}
However when I call the TTTableViewController from a TTTableSubtitleItem using the URL:
[TTTableSubtitleItem itemWithText:#"Locations Map" subtitle:#"Find a specific location" URL:#"tt://BuildingsLocationTableViewController/Loc"]
the loading screen does NOT show, it waits and then goes directly to the loaded table. Can anyone tell me why these call the TTTableViewController is different ways considering they both map through TTURLMap?
Thanks
JC
The mechanism, as you say, is just the same in both cases.
I would suggest checking your BuildingsLocationTableViewController model definition, and check the isLoadingselector, and the data source titleForLoading selector.
From there, if you debug, you should be able to find out a little more.
Ok hopefully this is an easy question:
I have a main viewcontroller that is loaded by the app delegate at application startup.
This viewcontroller has some code in 'viewDidLoad' to create some non view type based objects (some sound/data objects). Aside from that it also loads a UIView.
The sound/data objects take a while to create, but the app is quite functional without them for a start - so I want to load these objects after the UIView has loaded, but can't seem to figure out how.
I have tried moving the appropriate code to viewDidAppear, but this is still called before the UIView actually appears on screen. Is there a function that is called after the viewcontroller actually starts displaying UIViews, or any other way to achieve what I want?
Any help would be much appreciated - thanks!
In case anyone else has a similar problem, I found a way to solve it: use NSThread to load things in the background without pausing everything else.
There's a good simple example here: http://www.iphoneexamples.com/.
I'm using the three20 project for my iPhone app. I've narrowed my problem down and I'm now just trying to re-create the 'Web Images in Table' example that comes with the project. I've copied the code exactly as in the project, with the exception that I do not use the TTNavigator (which the example does) but I am adding my TTTableViewController manually to a tabBar.
The problem is as follows; the images in the table should load automatically from the web, like in the example. But they only load after I scroll the table up and down.
In the console it clearly says it is downloading the images, and you see the activity indicator spinning like forever.. And unless I scroll up and down once, the images will never appear.
Anyone? Thanks in advance.
P.S:
If I'm using this code in any random UIView, It also doesn't work (only shows a black square):
TTImageView* imageView = [[[TTImageView alloc] initWithFrame:CGRectMake(30, 30, 100, 100)] autorelease];
imageView.autoresizesToImage = YES;
imageView.URL = #"http://webpimp.nl/logo.png";
[self.view addSubview:imageView];
If I put this code in my AppDelegate (right onto the window), it does work .. strange?
POSSIBLE SOLUTION:
Although I stopped using TTImageView for this purpose, I do think I found out what the problem was; threading (hence accepting the answer of Deniz Mert Edincik). If I started the asynchronous download (because basically that is all the TTImageView is, an asynchronous download) from anywhere BUT the main thread, it would not start. If I started the download on the main thread, it would start immediately..
Sounds like a threading problem to me, are you creating TTImageView in the main runloop?
I find one interesting thing. When I use combination TTTableViewController, TTTableViewDataSource and TTModel I have same problem with loading TTImageView. My problem was, that my implementation of Model methods 'isLoading' and 'isLoaded' don't return proper values after initialization of model. That forces me to call reload on model manualy in 'viewDidAppear' method and that causes image loading problem. So I repair my 'isLoading' and 'isLoaded' methods to both return 'NO' after Model init, and everything is fine.
When an image finishes loading try sending a reloadData message to the table view. This forces the table to recalculate the size of the rows and redraw the table. Just be careful that you don't start downloading the image again in response to this message.
I've written something similar to this where an image view will load its own image from the web.
Im my experience, when the image had loaded successfully but was not shown in its view, it was a case that the cell needed to be told to redraw.
When you scroll the table view, the cells are set to redraw when the come onscreen, which is why they appear when you scroll.
When the image loads, tell the cell that it is sitting in to redraw by sending it the message setNeedsDisplay.
That way, when the image finishes downloading, the cell its sitting in (and only that cell) will redraw itself to show the new image.
It's possible that you might not need to redraw the entire cell and might be able to get away with simply redrawing the image view using the same method call. In my experience, my table cells view hierarchy was flattened, so I had to redraw the whole cell.
I don't have an answer for what you want to do, but I will say that this is considered a feature, and the expected behavior. You use TTImageView in UITableView when you want to do lazy loading of images. TTImageView will only load the images whose frames are visible on the screen. That way, the device uses its network resources to download images that the user has in front of them, rather than a bunch of images that the user isn't even trying to look at.
Consider having a long list that may contain a couple hundred thumbnail images (like a list of friends). I know from experience that if you kick off 100+ image requests on older devices, the memory usage will go through the roof, and your app will likely crash. TTImageView solves this problem.
This is a thread problem. You can load the images by including the line:
[TTURLRequestQueue mainQueue].suspended = NO;
in - (void)didLoadModel:(BOOL)firstTime.