In my program,I called subview from main superview with the following code: [self.viewaddSubview:mysubView.view]; I want to navigate from subview to previous superview like 'back function'.How can do like that? For My project,I use xCode 3.0.
You can use methods removeFromSuperview and bringSubviewToFront.
It sounds like what you really want is basic navigation bar functionality with a "back" button.
Check out UINavigationController and these two functions
- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
and
- (UIViewController *)popViewControllerAnimated:(BOOL)animated
at this documentation page:
http://developer.apple.com/library/ios/#documentation/UIKit/Reference/UINavigationController_Class/Reference/Reference.html
yes.You can,
sendSubviewToBack:
[self.view sendSubviewToBack:mysubView.view];
or
[mysubView.view removeFromSuperview];
You must get the object of subview in superView and store them into an array and than remove them according to there index position. If you use only single subview in super view than follow this code :
NSArray *arr = [SuperView subviews];
NSLog ("objects in arr %#",arr);
[[arr objectAtIndex:0] removeFromSuperview];
Related
Is this possible? Basically, I want to give my UIView a subview, and have that subview be in front of the view's layer (more specifically, in front of said layer's border).
Of course I could achieve the effect I want by making two subviews of the view's superview, one on top of the other. But I'd rather avoid that if possible.
I looked for this for a while myself; i don't believe it is possible. I solved the issue by, as you hint at, adding the subview and the parent to the same 'container' superview. Then its just a matter of ordering the two subviews, so that your subview is above the other and its border.
I solved this with a segue animation where i needed the sourceViewController to be in front of the destinationViewController. I had to remove the sourceViewController in order to re-nest it. My code looks like this:
- (void) perform {
UIViewController *sourceViewController = (UIViewController *) self.sourceViewController;
UIViewController *destinationViewController = (UIViewController *) self.destinationViewController;
UIView *parent = sourceViewController.view.superview;
[sourceViewController.view removeFromSuperview];
[parent addSubview: destinationViewController.view];
[parent addSubview:sourceViewController.view];
// Perform animation stuffs...
}
Following Scenario:
I have a = UIViewController A that contains a UIScrollView
I have a second UIViewController "B" (amongst other things it contains a button)
and add it to the ScrollView of A
myView *mView = [[myView alloc] init];
[myScrollView addSubview:mView.view];
Is there a way that once the button is pressed that it(view) removes itself from the scrollview?
I thought in the direction of setting the delegate of mView to "A" ?! But not sure how that should work in detail....
Any suggestions?
Thanks!
In the controller, you can call:
[self.view removeFromSuperview];
If you have a reference to view you can do the following:
[view removeFromSuperview];
If you don't have a reference, please post more code and I can modify my answer for you.
What is the difference between addSubview and insertSubView methods when a view is added programmatically?
The only difference is in where the view is added: whether it is the frontmost view (addSubview:), or it is before the 5th subview, (insertSubview:atIndex:) or if it is immediately behind another subview (insertSubview:aboveSubview:).
Using insertSubView: you can specify the index, which determines z-order of views. A view with a higher index lies above those with lower indices.
I don't think there is a difference. addSubview: is simple a convenient method for
[view insertSubview:aView atIndex:[view.subviews count]]
1.addSubview add subview in array then add in View'slayer
- (void)addSubview:(UIView *)subview
{
[_subviews addObject:subview];
[_layer addSublayer:subview.layer];
}
}
2.While insertSubview add your view as subview then call
[_layer insertSublayer:subview.layer atIndex:index];
- (void)insertSubview:(UIView *)subview atIndex:(NSInteger)index
{
[self addSubview:subview];
[_layer insertSublayer:subview.layer atIndex:index];
}
How can I make it so when a tab is selected, the current one is unloaded, and the next one is loaded so only one loaded at a time? Or should I not even do this? I know how to do it with a normal UIViewController as the root VC, but not sure with a UITabBarController. Also, is there a way to animate the transition from one tab to the next? Any help? Thanks!!
EDIT: ... If I unload the view controllers, then their icons on the tab bar are gone... maybe I'll just unload their views..
I can answer both questions in one...
You just need a class that acts as the UITabBarController delegate, then implement a method like so:
// Animate tab selections so they fade in and fade out
-(void)tabBarController:(UITabBarController*)tbc didSelectViewController:(UIViewController*)newSelection
{
[UIView beginAnimations:#"TabFadeIn" context:nil];
[UIView setAnimationDuration:0.6];
for( UIViewController* vc in tbc.viewControllers )
vc.view.alpha = (vc==newSelection) ? 1 : 0;
[UIView commitAnimations];
}
Now my code simply makes the tab bars fade in and out, but you could also do work here to unload non-used tabs. Sometimes that is a good idea if some of the tabs will be using a ton of memory.
You cant really manage the UITabBarController unfortunaly so you cant do lazy loading. You can by managining your own TabBar but you said u knew that already,
to manage your own tab bar though all you gotta do is setup a UITabBar with its TabBarItems in a ViewController, then implement the TabBar Delegate protocol, mainly the – tabBar:didSelectItem: method which is called whenever the tabbarItem selection is changed, then based on the item id you can load your new ViewController and release any others
so: Edit: this code goes in your UIViewController
-(void)addTabBar{
NSMutableArray* items=[[NSMutableArray alloc] init];
UITabBarItem *eventsItem= [[UITabBarItem alloc] initWithTitle:#"Events" image:nil tag:0];
UITabBarItem *albumItems=[[UITabBarItem alloc] initWithTitle:#"Album" image:nil tag:1]; //the tag is how you tell what was clicked
[items addObject:homeItem];
[items addObject:albumItems];
//MyTabBar is of type UITabBar
myTabBar=[[UITabBar alloc] initWithFrame:CGRectMake(0,411,320,49)];
[myTabBar setItems:items];
myTabBar.delegate=self; //you gotta implement the UITabBar delegate protocol
[myTabBar setSelectedItem:eventItem]; //set the selected item
[homeItem release];
[eventsItem release];
[albumItems release];
[items release];
[self.view addSubview:myTabBar]
}
then the protocol method would look something like below
- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item
{
if(item.tag == 0 )
{
//load the ViewController that pertains to this item and release others
}
...etc
}
Lazy loading is not an UITabBarController task. Instead, it is responsability of your viewControllers associated with your Tab.
To release the UIView, associated with each UIViewControllers, every time you change the TabBarItem, you must implement the following method in each UIViewController subclass, associated with your UITabBarController.viewControllers property:
-(void)viewDidDisappear {
[self.view removeFromSuperview];
self.view = nil;
}
Obviously, this will remove the self.view associated with your UIViewController. However, if your code is smart enough, this will remove all the related objects.
For example, suppose that your loadView method is as follow:
-(void)loadView {
UIView *contentVew = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
self.view = contentView;
…
...
UILabel *aLabel = [[UILabel alloc] initWithFrame:CGRectMake(0,0,320,50)];
…
…
[contentView addSubview:aLabel];
[aLabel release];
…
[contentView release];
}
This means that every object inside the contentView and their memory responsabilities are demanded to the contentView, that is released and attached to the self.view property.
In this scenario, removing the self.view (that's the reference to the contentView) resulting in a domino-style releasing of every object, that's your goal.
Best regards
Not sure why you'd want to do this, the current tab will get unloaded anyway if there's a memory issue involved. That's what -viewWillAppear, -viewDidUnload, etc. are for.
UITabBarController does lazy load all of its view controllers. When a tab is switched out, then it's view is subject to being deallocated in a memory tight situation. It is then recreated when it is chosen the second time. Furthermore, most of your memory hits are in your views and not the view controllers. Hence, don't worry about the memory hit from the view controller. The view is the proze.
If you are running on v3 of the OS, then you can use the -viewDidUnload method to ensure the maximal amount of memory reduction.
Andrew
I'm currently using this to unload inactive view controllers in the tab bar (based on Kendall's answer)
- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController: (UIViewController *)viewController {
// reload all inactive view controllers in the tab bar
for (UIViewController *vc in tabBarController.viewControllers) {
if(vc != viewController)
[vc didReceiveMemoryWarning];
}
}
In my app I have a tabBarController and in it a navigationController. One of my view controllers is a TableViewController and under the navigationBar i added a uiView as a subview to the view like this:
rectangleInfo = [[UIView alloc] initWithFrame:CGRectMake(0,0,[[UIScreen mainScreen] applicationFrame].size.width,26)]; rectangleInfo.autoresizingMask = (UIViewAutoresizingFlexibleWidth); rectangleInfo.backgroundColor = [UIColor darkGrayColor]; [self.view addSubview: rectangleInfo];
when I click on a cell in the tableView I push an UIViewController like this:
[feedViewController setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];
[[self navigationController] presentModalViewController:feedViewController animated:YES];
After i pop the modal view for a couple of times with it from the tableViewNavigationController disappears the rectangleInfo UIView.
I pop my modalview like this:
[[UIApplication sharedApplication] setStatusBarHidden:NO animated:YES];
[self setModalTransitionStyle:UIModalTransitionStyleCrossDissolve];
[self dismissModalViewControllerAnimated:YES];
any idea why that subview (rectangleInfo) of the tableViewController dissapears after i remove the modal view from the superview?
thank you in advance.
I'm curious as to what you are trying to do with your rectangleInfo view? By the size of it, it looks like you are trying to mimic the status bar. Why? You can just hide the status bar if you want.
Another thing you can try is to create the UIView visually in Interface Builder. Don't actually add it to your main view, but create it as a separate UIView in the XIB with the appropriate size, etc. Then create an outlet for it in Xcode and connect it. Next, add it as a subview in code when your view controller loads. See if that makes a difference. This is especially strange since you say it only disappears after popping it several times. Do you get the same problem if you push and pop the non-modal way, e.g.:
[[self navigationController] pushViewController:feedViewController animated:YES];
[[self navigationController] popViewControllerAnimated:YES];
i solved the problem by implementing correctly the viewDidLoad and viewDidUnload methods for creating and releasing my subviews.