Still learning about Objective C and getting the structure right.
I have an iOS App with a UIViewController that has a defined method named "doSomething". In my view controller I have a view and in that view a number of UIButton that I create programmatically (see example below with one button).
Now when I press the button I want to call my method "doSomething". The way I currently do it is like this:
[myButton addTarget:nil
action:#selector(doSomething:)
forControlEvents:UIControlEventTouchUpInside];
Since my target is nil it goes up the responder chain until it finds a method called "doSomething". It works, but it does not really feel right.
I have started to look into using #protocol but not really got my head around it. I have been looking at some tutorials but for me it is not clear enough. I have used protocols like for the table view controllers, but defining one is new for me.
Would it be possible to get an example for this specific case?
Thanks!
As your target pass in the view controller and the method will be called on that object.
Edit:
[myButton addTarget:controller
action:#selector(doSomething:)
forControlEvents:UIControlEventTouchUpInside];
Assuming that you have a variable called controller that is your UIViewController. If you don't have a reference to your controller then simply pass one to your view.
Edit2:
View interface:
#property (assign) UIViewController* controller;
View implementation:
#synthesize controller;
Controller:
- (void) viewDidLoad {
[super viewDidLoad];
someView.controller = self;
}
The way I'd do it is set the value of addTarget to self.
[myButton addTarget:self
action:#selector(doSomething:)
forControlEvents:UIControlEventTouchUpInside]
This will look for the method doSomething on the object that the target is added in. In this case, this would be the view controller.
Related
I have a problem on how to properly do a certain kind of action.
The image below shows a UIViewController, but the second part of the view is a custom UIView (the one with the profile pic, name and Show View button).
The subclassed UIView is allocated using this code:
profileView = [[GPProfileView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 70)];
profileView.myTripGradientColor = YES;
[self.view addSubview:profileView];
The problem is of course, that the button on the UIView can't show any view, since it's only the UIViewController that can push another ViewController to the window(correct?).
The UIView is used in several places in the app and needs to be added easily and have the same behavior across the application.
This worked great until I added the button, and I'm starting to think I've made this wrong, and there has to be a better way to do it (maybe change the UIView to something else?).
I was thinking I should be able to call:
self.superview
And then somehow get the ViewController so I can push another ViewController into the view hierarchy, but nope.
Any suggestions and a tips on how to do this correctly?
UPDATE:
I have no idea on how to push another UIViewController from the button.
What should I do in this method when pressing the button in the UIView:
- (void) showViewButtonTouched:(UIButton*)sender {
GPProfileSocialFriendsViewController *friendsSettings = [[GPProfileSocialFriendsViewController alloc] init];
}
How do I push GPProfileSocialFriendsViewController?
Your - (void) showViewButtonTouched:(UIButton*)sender method should be in your controller and would probably be better named - (void) showView:(UIButton*)sender or - (void) showProfile:(UIButton*)sender so it clearly denotes what it does (not how you got there).
It's not the view's responsibility to manage transitions from a state to another. If you move your method to your controller, your problem is no more (you can easily access self.navigationController or push directly if you don't have an navigation controller like this:
[self presentViewController:vcThatNeedsToBePushed animated:YES completion:nil];
I think you can create weak reference in GPProfileView on UIViewController. Like this:
#property (weak, nonatomic) UIViewController *rootController;
when you create GPProfileView, assign rootController-property:
profileView = [[GPProfileView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 70)];
profileView.myTripGradientColor = YES;
profileView.rootController = self; // if view created in view controller
[self.view addSubview:profileView];
and in implementation of button selector:
self.rootController push... // or pop
May be this not correct, but you can try
You could let the view controller push the next view controller when the button is pushed. The view controller can add a target/action on the button, so that the action method in the view controller is called on the touch up inside event.
I have a storyboard app with two different ViewController. On the second ViewController I have a UIImageView and I would like to call that UIImageView on the first one. I've been looking for a solution but I can't find anything that work for me.
#property(nonatomic, retain) IBOutlet UIImageView *pic;
I just want to be able to use that UIImageView on the other viewcontroller. I hope you can help me.
EDIT:
yes you can try to set your UIImageView in prepare for segue. I have tried it and it seems to work. You would do it as follows:
**I am assuming that the controller you are seguing to is called NewViewController
**I am also assuming your NewViewController has a UIImageView called imageView
-(void)prepareForSegue....
{
if ([segueIdentifier isEqual....])
{
NewViewController *newController=(NewViewController *)[segue destinationViewController];
[[newViewController imageView]setImage:self.someUIImageFromCurrentClass];
[[newViewController imageView]setNeedDisplay];
}
}
and yes, you do have to create a UIImage in current class (in this case it's self.someUIImageFromCurrentClass). That's the point is that you're taking an image from current ViewController (current class) and showing it in the ViewController you are seguing to.
ORIGINAL:
-(void) prepareForSegue: (UIStoryboardSegue *)segue sender:(id)sender
{
if ([segue.identifier isEqualToString:#"your segue name"])
{
[segue.destinationViewController setYourUIImage:self.someImageFromCurrentClass];
}
}
be sure to import the .h file for the controller you're seguing to.
second, YourUIImage is an UIImage that is publicly declared in the controller you're seguing to (like Michael mentioned).
In the destination controller, you'll want to grab that UIImage and set it as the image for you UIImageView:
[self.myImageView setImage:YourUIImage]; // <-- you can do this in ViewDidLoad or ViewWillAppear
that should get you going
**Also I guess it's worth mentioning is that a segue always creates a new instance of the controller you're seguing to, which doesn't exist before the segue, which is why you have to pass the image to it.
You can't use outlets between view controllers (VCs) because there's no automatic one for one VC to refer to another. You'll have to expose public properties or methods that allow the manipulation you need and find some way to pass a reference to one VC from another.
For example, if you pass from one VC to another via a segue, you can manipulate properties in the destination VC from the source in prepareForSegueWithIdentifier:.
Okay so I feel like there's something obvious I'm missing in this question. I've used makeFirstResponder throughout my code to move from textField 1 to 2, 2 to 3, etc. That seems to work as I want it to, yet when the new view is loaded, I want the cursor to be in textField1, and yet the following code does not place the cursor in textField1 upon load.
- (void) awakeFromNib{
[[[self view] window] makeFirstResponder:textField1];
}
I also tried setInitialFirstResponder, and that didn't have any effect either (I don't even think that would be right.) So, is it because it is in the awakeFromNib method? Can anyone tell me what I'm missing? Thanks in advance.
EDIT - My solution was differed slightly from the accepted answer so I thought I'd post my implementation. Because the view I wanted to set the first responder for was a subview added later (think the second screen of an application wizard), I simply added a setCursorToFirstTextField method:
- (void) setCursorToFirstTextField {
[[[self view] window] makeFirstResponder:textField1];
}
And made sure to call it after I had added the subview to the custom view on the original window.
Yes, you're right about the problem being the location of the method in awakeFromNib. If you log [self.view window] in your awakeFromNib, you'll see that it's NULL. I don't know how exactly you have things set up, but I'm guessing (if this relates to your WizardController question) that you're doing an alloc initWithNibName:bundle: in another class to create your view controller and then adding that controller's view to the view hierarchy. If you throw some logs in there, it will show you that awakeFromNib in the controller class is called after the alloc init, but before the view is added as a subview, so there is no window at that time. The way I got around this problem was to create a setup method in the view controller class (with the makeFirstResponder code in it), and call it from the class where you create the controller after you add it as a subview.
- (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
self.wizard = [[WizardController alloc] initWithNibName:#"WizardController" bundle:nil];
[self.window.contentView addSubview:wizard.view];
[self.wizard doSetup];
}
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
I might be confused here and asking the wrong question.
If I use a class like the UISplitViewController inside the appdelete.m, will the only message i will receive is the message the UISplitViewController calls and not any VIEW message? for example:
in my myappdelegate.m
....
UISplitViewController *mySplitViewController = [[UISplitViewController alloc] init];
mySplitViewController.viewControllers = [NSArray arrayWithObjects:leftside,rightside,nil];
...
mySplitViewController.delegate = self;
....
[windows addSubView:mySplitViewController.view];
....
-(void) viewWillAppear:(BOOL) animated {
}
in myappdelegate.h I included UISplitViewControllerDelegate
I expected viewWillAppear to fire but it is not. I assume if I had subclass UISplitViewControler it would have fire. right?
BTW: I am doing this without using IB. Do I need to set the target for the mySplitViewController?
What I want to do is setup the orientation of the splitviewcontroller when it rotates.
the viewWillAppear method and other view related methods will be called on the view or view controller themselves, not on the delegate.
That means that if you make a subclass of UISplitViewController called SplitViewControllerSubClass, the view... methods will be called on the instance of SplitViewControllerSubClass, not on the delegate object.
But considering you are creating the views and displaying them programmatically, you already know exactly when the view will appear (i.e., right before you add it to the window), so I believe you could do whatever setup you want at that point.