I am going through some sample code from Apple. The following 5 statements are from MoveMeAppDelegate.m belonging to the "MoveMe" sample project:
UIViewController *aViewController = [[UIViewController alloc] initWithNibName:#"MoveMeView" bundle:[NSBundle mainBundle]];
self.viewController = aViewController;
[aViewController release];
UIView *controllersView = [viewController view];
[window addSubview:controllersView];
From documentation, #"MoveMeView" defines the name of a xib file. But it seems that a xib file can have more than one view object. And in the last statement above, the controllersView is added to a window object. My question is if the window has more than one view, then how does the compiler know which view is the above codes referring to ?
If you're asking how your app knows which view is the controller's view: in your .xib file, you "attach" one of the views to the controller. This relationship is called an outlet, and in code is signified by the IBOutlet tag on an instance variable or on a property.
For more information, check out Apple's Resource Programming Guide--specifically, the section entitled "Nib Files."
If you're asking how the window knows which views belong to it: a window on iOS is also a view, and can have a (nearly) unlimited number of subviews.
If you're asking something else... I don't know what you're asking, so please clarify.
Related
In short, how can i manage to load a SPECIFIC uiview from a set of UIViews all contained in one XIB file? iboutlets? how?
In some cases i would like the first view displayed instead of the 2nd, sometimes i want the 3rd displayed instead of the 1st. they are all similar UIViews however only one can be displayed MODALLY presented.. I know which UIView to display depending on the user interaction with buttons being clicked.. however the question is how can i specifically select a certain view to be displayed and then attach it modally to present it.
In detail this is what i have done so far:
Hi,
I have three view objects inside my TestViewController.xib file like so:
This xib's 'File's Owner' is connected to a TestViewController class.
On run time i am programatically instantiating the TeamViewController class like so:
TestViewController *tVController = [[TestViewController alloc] initWithNibName:#"TestViewController" bundle:nil];
I then present the view modally like so:
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:ls];
[nav setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
[nav setModalPresentationStyle:UIModalPresentationFormSheet];
nav.navigationBar.tintColor = [UIColor blackColor];
[nav setNavigationBarHidden:YES];
[rootViewController.navigationController presentModalViewController:nav animated:YES];
nav.view.backgroundColor = [UIColor blackColor];
self.modalNavController = nav;
[nav release];
[tVController release];
This all works and my view is loaded, however it only loads one of the views by default - automatically.
What i would like to do is to be able to know how to load only a SPECIFIC UIView when instantiating the TestViewController. One way i thought of achieving this was to create IBOutlets for them and managing which view is displayed like that? so I have created three IBOutlets within the class and then connected them from the Xib's fileown to each UIView. This connected all fine.
IBOutlet *view1;
IBOutlet *view2;
IBOutlet *view3;
I am able to do something like this:
[self.view addSubview:view2];
and this will display view2 properly, however not in the modal view as i would ideally like it when instantiating TestViewController.
Can anyone guide me in how to achieve this goal of mine?
Thanks
You should give each of the views a unique tag, then use viewWithTag:
-EDIT-
In order for this to work, you might need to do NSNib *n = [[NSNib alloc] initWithNibNamed:bundle:]
Can anyone tell me how (or direct me to info on) displaying a .xib (nib) on another .xib (nib).
How ever I wish to place it so I can programically move it around the main nib sort of like this (which obviously doesn't work)
- (void)drawRect:(NSRect)dirtyRect
{
NSRect customView = NSMakeRect(pos1, pos1, 200, 100);
[[NSBundle mainBundle] loadNibNamed:#"secondXib" owner:self];
NSRectFill (customView);
}
And I wish to do this for Mac OS X (Not iPhone). (By the way using xCode 4 incase it makes a difference)
You can easily load a view from another nib using NSViewController. In your nib you should just set File's Owner's custom class to NSViewController and hook up the view outlet of File's Owner to point to the view you want to load. You can then just do this:
//create an NSViewController and use it to load the nib
NSViewController* vc = [[NSViewController alloc] initWithNibName:#"YourNibName" bundle:nil];
//get the view from the view controller
NSView* loadedView = [vc view];
//release the view controller so we don't leak
[vc release];
//add the view as a subview of your main view
[mainView addSubview:loadedView];
//position the view
[loadedView setFrameOrigin:NSMakePoint(100.0, 100.0)];
You don't need to do anything in drawRect:. The subview will draw itself, and drawRect: will be called automatically if you move the subview.
You should read the View Programming Guide for Cocoa. It is critical to understanding how views work, and it is clear from your question that you do not yet have that understanding.
You should also read the Cocoa Drawing Guide.
Thanks a lot,
Another alternative ( which is basically the non programming way of doing it ), is to add a NSViewController object in your first xib, and set it to you use the nib name that you specify.
In your second xib, don't forget to set the class name in the "custom class" field on the view ( and NSViewController on file's owner ) else that won't work.
I can't seem to figure this out for the life of me. I have a custom table view cell, in that cell I have a few buttons configured. Each button connects to other view controllers via a storyboard segue. I've recently removed these segues and put a pushViewController method in place. Transition back and forth across the various views works as expected however the destination view controller is not displaying anything! I have some code below as an example.
Buttons have this method set:
[cell.spotButton1 addTarget:self action:#selector(showSpotDetails:) forControlEvents:UIControlEventTouchUpInside];
// etc...
[cell.spotButton4 addTarget:self action:#selector(showSpotDetails:) forControlEvents:UIControlEventTouchUpInside];
// etc...
showSpotDetails Method contains this code:
- (void)showSpotDetails:(id)sender
{
// determine which button (spot) was selected, then use its tag parameter to determine the spot.
UIButton *selectedButton = (UIButton *)sender;
Spot *spot = (Spot *)[spotsArray_ objectAtIndex:selectedButton.tag];
SpotDetails *spotDetails = [[SpotDetails alloc] init];
[spotDetails setSpotDetailsObject:spot];
[self.navigationController pushViewController:spotDetails animated:YES];
}
The details VC does receive the object data.
- (void)viewDidLoad
{
[super viewDidLoad];
NSLog(#"spotDetailsObject %#", spotDetailsObject_.name);
}
The NSLog method below does output the passed object. Also, everything in the details view controller is as it was. Nothing has changed on the details VC. It just does not render anything ever since I removed the segue and added the pushViewController method. Perhaps I am missing something on the pushViewController method? I never really do things this way, I try to always use segues...
Any suggestions?
Welcome to the real world. Previously, the storyboard was a crutch; you were hiding from yourself the true facts about how view controllers work. Now you are trying to throw away that crutch. Good! But now you must learn to walk. :) The key here is this line:
SpotDetails *spotDetails = [[SpotDetails alloc] init];
SpotDetails is a UIViewController subclass. You are not doing anything here that would cause this UIViewController to have a view. Thus you are ending up a with blank generic view! If you want a UIViewController to have a view, you need to give it a view somehow. For example, you could draw the view in a nib called SpotDetails.xib where the File's Owner is an SpotDetails instance. Or you could construct the view's contents in code in your override of viewDidLoad. The details are in the UIViewController documentation, or, even better, read my book which tells you all about how a view controller gets its view:
http://www.apeth.com/iOSBook/ch19.html
The reason this problem didn't arise before is that you drew the view in the same nib as the view controller (i.e. the storyboard file). But when you alloc-init a SpotDetails, that is not the same instance as the one in the storyboard file, so you don't get that view. Thus, one solution could be to load the storyboard and fetch that SpotDetails instance, the one in the storyboard (by calling instantiateViewControllerWithIdentifier:). I explain how to do that here:
http://www.apeth.com/iOSBook/ch19.html#SECsivc
Lets say that I have 4 view controllers (call them FirstView,SecondView,ThirdView,FourthView) which are created programmatically and all are in separate files:
In AppDelegate.m didFinishLaunchingWithOptions method I have these lines of code
self.rootViewController = [[rootViewController alloc]initWithNibName:#"rootViewController" bundle:nil];
self.window.rootViewController = self.rootViewController;
In rootViewController.m loadview method I have
self.view = [[UIView alloc]initWithFrame:[UIScreen mainScreen].applicationFrame];
self.firstView = [[FirstView alloc]init];
[self.view addSubview:self.firstView.view];
That code works fine - first view is displayed.
Let's continue
In FirstView.m switchViews method
NOTE: Please see the comments in code
self.secondView = [[SecondView alloc] initWithNibName:#"SecondView" bundle:nil];
// I think here secondView is added to rootViewController - right ?
[self.view.superview addSubview:self.secondView.view];
// Here first view is removed from rootViewController - right ?
[self.view removeFromSuperview];
Here is how I add/remove views.
Is this approach correct?
Can you recommend a better solution?
I have read about UINavigationController, but I don't think it could be a solution in this case.
You say:
I have 4 views (call them FirstView ...
Then you say:
[self.view addSubview:self.firstView.view];
Which makes me think that FirstView isn't actually a UIView - as you claim it is. Instead, it's probably a UIViewController - a different beast altogether.
If my suspicion is correct - then you are "off-track" so to speak.
Going beyond that to your sample code snippet:
self.secondView = [[SecondView alloc] initWithNibName:#"SecondView" bundle:nil];
// I think here secondView is added to rootViewController - right ?
[self.view.superview addSubview:self.secondView.view];
// Here first view is removed from rootViewController - right ?
[self.view removeFromSuperview];
This is definitely not a great idea. Here's why:
First: your view controller doesn't explicitly "know" anything about the superview you are so casually inserting and removing subviews to/from - so it shouldn't do that. You may, alternatively, create your own view and insert/remove subviews from that - which would not only be perfectly acceptable but also common practice.
Second: if these are actually UIViewControllers like I think they are - then you are not properly handling hooking them up to the UIViewController event chain - which means methods on these subclasses like viewDidAppear: or viewDidUnload will not fire.
From what I see in your code, UINavigationController seems like it would help. If you don't want a navigation bar, you can definitely hide it, but the methods in UINavigationController should help you with switching views.
If your views only need to display temporarily, you could also use Modal View controllers. An example of Modal View controllers can be found here.
If you haven't already, check out the View Controller Programming Guide from Apple.
Just because I am unable to find a secure way (in a sense that it can be rejected by Apple guys) to customize UITabbar, in particular UITabBarItem I am trying some workaround.
I have a main view on which I recreate a kind of UITabBar, a normal view with two buttons inside. This is (roughly) the current hierarchy:
-MainView
--placeholder(UIView)
--fakeTab (UIView)
What I want to do is, after tapping a button in fakeTab, build a UINavigationController and add it to "placeholder" view so that the fakeTab remain on top and the whole navigation happens on the placeholder level.
I already tried with this piece of code in the method that it's intercepting tap button, and it works, I can see the ipvc.view added to placeholder.
IPPlantsViewController *ipvc = [[IPPlantsViewController alloc] initWithNibName:#"IPPlantsView" bundle:[NSBundle mainBundle]];
UINavigationController *nav = [[UINavigationController alloc] initWithRootViewController:ipvc];
UIView *placeholder = [self.view viewWithTag:200];
[placeholder addSubview:ipvc.view];
But later when I call from inside ipvc, then nothing happens:
IPAttributes *ipas = [[IPFactory findPlantByIndex:indexPath.row] attrs];
[self.navigationController pushViewController:ipa animated:YES];
I find the solution myself. What I was doing wrong is to attach the ipvc controller view to placeholder. Instead of doing this:
[placeholder addSubview:nav.view];
and everything works as expected, with my fake tabbar fully customized :-)
But, as a side note, the viewWillAppear seems to be never called.
It would be interesting to know why. I partially solved by making IPPlantsViewController the delegate of the UINavigationController.