So, I have a HomeViewController (picture 1) with two buttons, one white and one blue. On the right bottom corner you can see a button which modally presents a SettingsViewController (picture 2), on this view controller there are 4 buttons so the user can choose which color scheme do they prefer. Imagine the user press the first one (red) then, when dismissing the view controller the color scheme of HomeViewController should look like picture 3.
Any ideas on how to do this on a efficiently/simple way?.
There are two good ways you could do this: 1) Delegation, and 2) viewWillAppear:.
For delegation, you'll need to define a protocol. Your HomeViewController will be a delegate for this protocol, and your SettingsViewController will call it.
//SettingsViewController.h
#protocol SettingsDelegate <NSObject>
#required
-(void)colorChanged:(UIColor *)color;
#end
#interface SettingsViewController : UIViewController
#property (nonatomic, weak) id<SettingsDelegate> delegate;
#end
Somewhere when the settings view controller is set up, make sure to set self.delegate equal to a reference to HomeViewController. This is a must.
Then, when your user changes the color, call:
[self.delegate colorChanged:whateverColor];
Your delegate must obviously observe this method, and change the color appropriately:
-(void)colorChanged:(UIColor *)color {
[myButton setBackgroundColor:color];
}
For viewWillAppear:, just save the color somewhere and set the color of your button in your view controller's method for this. viewWillAppear: will get called when your settings view is about to disappear and show the home view controller:
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[myButton setBackgroundColor:mySavedColor];
}
In HomeViewController
On SettigButton Click
{
Pass the HomeViewController delegate object SettingsViewController
Present your color Picker SettingsViewController
}
In SettingsViewController
Define protocol name SettingsViewControllerDelegate
{
-(void)selectedColor:(UIColor*)color;
}
return the selected color On dismissViewController
if(delegate)
{
[delegate selectedColor:color];
}
Again In HomeViewController
-(void)selectedColor:(UIColor*)color
{
view.backgroundColor=color;
}
Related
I need to hide an UIImageView, from an action triggered by a UISwitch which is inside a popover.
I'm using this piece of code however it does nothing when tapping the UISwitch, probably because the UISwitch its inside a popover view.
This code works perfectly on iPhone, however on iPad does not work and the UIImageView does not hide. Why?
- (IBAction)toggleImage:(id)sender {
if ([sender isOn]){
self.myImage.hidden = NO;
} else {
self.myImage.hidden = YES;
}
}
UIImageView is connected to an outlet and UISwitch is connected to an outlet and action.
Please help, thank you.
Since the switch being interacted with is on the popover and the image view that we want to change is on the underlying (presenting) VC, the proper approach is to make the underlying VC a delegate of the popover.
// MyPopoverVC.h
#protocol PopoverDelegate <NSObject>
- (void)popover:(MyPopoverVC *)vc changedSwitchTo:(BOOL)on;
#end
#interface MyPopoverVC : UIViewController
#property (nonatomic, weak) id<PopoverDelegate>delegate;
// ...
#end
In the Popover VC's implementation (IMPORTANT: the switch's IBAction should be wired to the popover vc)...
- (IBAction)toggleImage:(UISwitch *)sender {
[self.delegate popover:self changedSwitchTo:sender.on];
}
In the presenting vc, declare it as conforming to that <PopoverDelegate> protocol. Before presenting the popover, initialize the delegate...
MyPopoverVC *myPopoverVC = [[MyPopoverVC alloc] init...
myPopoverVC.delegate = self;
Also in the presenting vc, implement the delegate protocol...
- (void)popover:(MyPopoverVC *) changedSwitchTo:(BOOL)on {
self.myImage.hidden = !on;
}
I want to segue back from ViewControllerTwo to ViewControllerOne. I created a button that is responsible for doing that, but my problem is that the button is part of custom UIView class that is added to ViewControllerTwo, the button is not a part of the main view of ViewControllerTwo.
So in the custom UIView class I have the method that reacts if the button is clicked...
-(void)buttonClicked{
[SecondViewController performSegueWithIdentifier: "ShowFirstViewController" sender:nil];
}
When I do this I get an error: "performSegueWithIdentifier not a method of class" which makes sense.
So how can I segue between two viewcontrollers where the button responsible for the segue is not actually part of either view controller and is in a different class.
I think you can have a delegate call back to your SecondViewController and implement the performSegueWithIdentifier in the delegate callback method in SecondViewController.
It goes like this:
Above your custom UIView class interface create a protocol like this
#protocol CustomViewDelegate <NSObject>
- (void)buttonDidTap;
#end
Then create a property in your interface
#property (nonatomic, weak) id <CustomViewDelegate> delegate;
In your custom UIView *.m add this
-(void)buttonClicked{
[self.delegate buttonDidTap];
}
Conform the protocol to your SecondViewController like this
#interface SecondViewController: UIViewController <CustomViewDelegate>
set the delegate in your viewDidLoadMethod like this
-(void)viewDidLoad{
[super viewDidLoad];
self.yourCustomView.delegate = self;
}
implement this method inside the view controller .m file
- (void)buttonDidTap{
[self.performSegueWithIdentifier: "ShowFirstViewController" sender:self];
}
I'm more of a swift guy i think this should work fine.
iOS 9.3, Xcode 7.3, ARC enabled
This is what I'd do to troubleshoot:
Step 1: Make sure that you have a proper storyboard identifier for the view controllers you wish to segue between. The views simply attach to the view controllers, custom or not.
To do this, go to "*.storyboard" show the Utilities (right pane) and navigate to the Identity Inspector. Make sure you have "ShowFirstViewController" entered in the Storyboard ID field.
I have a UINavigationController that I reuse to push photos and comments looping over each other through the navigation controller.
In my MyViewController.h:
#property (nonatomic, strong) NSMutableAttributedString *pLabel;
In my MyViewController.m:
- (void) viewWillDisappear:(BOOL)animated
{
if ([self.navigationController.viewControllers indexOfObject:self] == NSNotFound)
{
// A photo function gets the right label
_pLabel = // function gets correct label I want
}
[super viewWillDisappear:animated];
}
- (void)viewWillAppear:(BOOL)animated
{
_pLabel = // is already set
}
I click on MyViewController once and set mvc.pLabel = #"1st one". Then I click a button to create a new MyViewController and set mvc.pLabel = #"2nd";
Then when I click the Back button viewWillDisappear gets called and my dictionary sets pLabel = #"1st". Then viewWillAppear gets run to show the first navigation controller view and pLabel = #"2nd";
Why isn't viewWillDisappear not saving the pLabel?
Thanks.
Your property is bound to 1 instance of MyViewController so when you pop your second view controller you'll set the property of the MyViewController that will disappear and not to the one that'll become visible.
If you don't keep a reference on the MyViewController that disappears there are no reason to update one of its label, since you'll probably show a fresh new instance of MyViewController next time.
I am relatively new to Xcode and have tried to find the answer by searching, without luck.
My app has 5 View Controllers, V1 through V5, which are embedded in one Tab Bar Controller. Each View Controller has a segue to one and the same Setup Menu View Controller. The Menu changes some labels on the View Controllers. I use a delegate to make sure that the View Controller that calls the Menu gets updated with the new settings when you leave the Menu. However, this allows me to modify only the labels on the View Controller that called the Menu Controller, not on the 4 other ones.
I work form a Story Board. Is there a simple way to set the UILabels on V2, V3, V4 and V5 from V1 (and vice versa), or even better, set the labels on V1 through V5 from the Menu View Controller (which is not embedded in the Tab Bar Controller)?
I have seen something that could help here, but this seems rather complicated for what I want. The label changes I need are quite simple and are all predefined. Is there a method that is called every time you switch tabs in a tabbed application? Similar to ViewDidLoad?
This sounds like a good time for NSNotificationCenter. You are going to have your MenuViewController generate a notification with the new data that should be updated in your other view controllers:
// User has updated Menu values
[[NSNotificationCenter defaultCenter] postNotificationName:#"MenuDataDidChangeStuffForLabels" object:self userInfo:#{#"newLabelValue" : labelText}];
In your V1, V2, etc. you can add subscribe to these notifications using this code in your viewDidLoad method:
- (void)viewDidLoad {
[super viewDidLoad];
// Subscribe to NSNotifications named "MenuDataDidChangeStuffForLabels"
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(updateLabelText) name:#"MenuDataDidChangeStuffForLabels" object:nil];
}
Any object that subscribes using that code will call the updateLabelText method anytime a notification with that name is posted by the MenuViewController. From that method you can get the new label value and assign it to your label.
- (void)updateLabelText:(NSNotification *)notification {
NSString *newText = notification.userInfo[#"newLabelValue"];
myLabel.text = newText;
}
What I would do is subclass the tab bar controller and set that as the delegate for the menu view controller. From there, you can get updated when the labels are supposed to change and then communicate with the 5 tabs and update the labels.
Alternatively, you could use NSNotifications to let all the 5 view controllers know when settings change.
Lastly, you could add the menu settings to a singleton and have all of the view controllers observe the various properties that can change.
The label changes I need are quite simple and are all predefined. Is there a method that is called every time you switch tabs in a tabbed application? Similar to ViewDidLoad?
Regarding this question, the methods you're looking for are viewWillAppear: and viewDidAppear.
Here is a very simple solution if your workflow is also simple. This method changes all the labels from the different ViewControllers directly from what you call the Menu ViewController.
Let's say you have the following situation :
The blue ViewController is of the FirstViewController class. The green ViewController is of the SecondViewController class. The labels on each of those are referenced by the properties firstVCLabel and secondVCLabel (on the appropriate class' header file). Both these ViewControllers have a "Modal" button which simply segues modally on touch up inside.
So when you clic on any of these two buttons, the orange ViewController (of ModalViewController class) is presented. This ViewController has two buttons, "Change Label" and "Back", which are linked to touch up inside IBActions called changeLabel: and back:.
Here is the code for the ModalViewController :
#import "ModalViewController.h"
#import "FirstViewController.h"
#import "SecondViewController.h"
#interface ModalViewController ()
#end
#implementation ModalViewController
// Action linked to the "Change Label" button
- (IBAction)changeLabel:(id)sender {
// Access the presenting ViewController, which is directly the TabBarController in this particular case
// The cast is simply to get rid of the warning
UITabBarController *tabBarController = (UITabBarController*)self.presentingViewController;
// Go through all the ViewControllers presented by the TabBarController
for (UIViewController *viewController in tabBarController.viewControllers) {
// You can handle each ViewController separately by looking at its class
if ([viewController isKindOfClass:[FirstViewController class]]) {
// Cast the ViewController to access its properties
FirstViewController *firstVC = (FirstViewController*)viewController;
// Update the label
firstVC.firstVCLabel.text = #"Updated first VC label from Modal";
} else if ([viewController isKindOfClass:[SecondViewController class]]) {
SecondViewController *secondVC = (SecondViewController*)viewController;
secondVC.secondVCLabel.text = #"Updated second VC label from Modal";
}
}
}
// Action linked to the "Back" button
- (IBAction)back:(id)sender {
[self.presentingViewController dismissViewControllerAnimated:YES completion:nil];
}
For the sake of completeness, here are FirstViewController.h :
#import <UIKit/UIKit.h>
#interface FirstViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *firstVCLabel;
#end
And SecondViewController.h :
#import <UIKit/UIKit.h>
#interface SecondViewController : UIViewController
#property (weak, nonatomic) IBOutlet UILabel *secondVCLabel;
#end
There is no relevant code in the implementation of these classes.
Thanks a lot guys, I am impressed by your quick responses. In this particular case, viewWillAppear does the trick:
- (void)viewWillAppear:(BOOL)animated
{ [self AdaptLabels];
NSLog(#"View will appear.");
}
Every time a new tab is chosen, it updates the labels in the new View, according to a global variable set by the Menu, just before they appear. Very quick and clean. Thanks to all of you!
I have a ViewController with 2 sub containers. The first sub container points to a ViewController with a TabBar inside it. The second sub container is a ViewController that contains a collection view. Now my issue is trying to access the first sub containers TabBar so that when an Item is clicked, I can know which item is clicked and process my data.
The main ViewController has a class. All the other sub containers for that ViewController also have a class. Here is the .h for my sub container with the Tab Bar:
#import <UIKit/UIKit.h>
#interface home_tab : UIViewController <UITabBarControllerDelegate>{
}
#end
.m:
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
-(void) tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
NSLog(#"working");
}
Now when clicking on the Tab Bar that is populated, didSelectViewController is never called.
I am using storyboard.
Suggestions and thoughts?
Try this on your viewDidLoad
- (void)viewDidLoad
{
[super viewDidLoad];
[[self tabBarController]setDelegate:self];
// Do any additional setup after loading the view, typically from a nib.
}
It's just an suggestion :)
[[self tabBarController]selectedIndex] This will return the index of the selected tab.
I think you have a couple problems atleast from what I can see here,
You are using a TabBar inside of a ViewController, not a UITabBarController, thus you need to use UITabBarDelegate not UITabBarControllerDelegate. You will have to manage the view controllers or whatever view you will want to be loaded on your own most likely with the delegate callback:
-(void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item;
Also you dont have a UITabBar defined in your controller, therefore your ViewController has no idea you have a UITabBar in your Storyboard. You need something like this:
#interface ViewController : UIViewController <UITabBarDelegate>
#property (weak, nonatomic) IBOutlet UITabBar *tabBar;
#end
Then you will need to Control drag from the ViewController to your UITabBar and back to connect the Delegate in your Storyboard.
Id recommend using a UITabBarController so you dont have to manage the views yourself depending on what you are trying to accomplish.
Hope this helps!
the didSelectViewController method is part of the UITabBarControllerDelegate Protocol and is called on the UITabBarController's delegate. Did you set the delegate of the tab bar controller to the current instance of your subcontainer? Inside ViewDidLoad: do something like this:
[self.tabBarController setDelegate:self];
You can also set a delegate on the UITabBar rather than the controller, and the UITabBarDelegate Protocol contains a method tabBar:didSelectItem: that would be called.