Change (not init) a UIBarButtonItem identifier programmatically? - iphone

In IB I can set the identifier of a UIBarButtonItem to 'play' which adds an image of a play button (right-pointing triangle).
Is there a way to change this image programmatically? I want to change it to 'pause' when the play button is pressed.
I know you can initialize a UIBarButtonItem with an identifier but I've yet to find a way to change it after it's been initialized. Is this even possible?
The only thing I can think of is to remove the old button and initialize a new one in its place, but this hardly seems efficient.
Any thoughts?

Ok I've googled this question to death and ran into sample code from Apple where they do exactly the same thing (toggle play/pause button graphic on a toolbar button). But instead of using the built in play and pause identifiers of UIBarButtonItem they use a custom UIButton and toggle custom images.
So if Apple goes through the trouble of creating and toggling custom images on a UIButton instead of the built in play and pause UIBarButtonItem buttons then I think it's pretty safe to say there's no way to programatically change the identifier of a UIBarButtonItem.
This is what they (Apple) do to toggle the images when the button is pressed:
// Call this when the button you want to toggle is pressed:
[playButton setImage:((p.playing == YES) ? pauseBtnBG : playBtnBG) forState:UIControlStateNormal];
Replace p.playing with whatever BOOL you want to hold the state of your button. playButton is the custom UIButton in the toolbar. pauseBtnBG and playBtnBG are the images to toggle.

This seems to work fairly well:
UIBarButtonItem *oldButton = [myToolBar.items objectAtIndex:1];
[myToolBar setItems:[NSArray arrayWithObjects:[myToolBar objectAtIndex:0], [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemStop target:self action:#selector(tapStopRefreshButton:)],nil] animated:NO];
[oldButton release];
In this example I had a toolbar for a UIWebView and when someone clicked Reload I wanted it to change to Stop. The toolbar only had a flexible space and the one button on it - to right-align the button - so I grabbed a reference to the old button, made a new one with the same selector as the old, reset the buttons on the tab bar, and then released the original button.
Not the prettiest, but you can use all standard buttons without having to override the button class(es).

What about 2 stacked toolbars? Then you can have some system buttons in the top one, and others in the bottom one. If the play button is pressed, then just hide the top toolbar.

Related

Custom UIBarButtonItem highlight issue

I have a toolbar with 5 buttons.
4 of them are regular bar button items and one of them is a custom one (A 'UIButton' inside a 'UIBarButtonItem').
I noticed that when I click between the regular buttons (not exactly on them), one of them (the closest one) still recieves the click event and is being highlighted (which is what I want).
But the custom bar button item does not show this behaviour.
When I tap between it and one of the regular buttons neither of the 2 receives the touch event. This probably because the UIButton is the one the gets the click event. Is there a way to add a touch event the containing bar button item as well? Or perhaps another way to solve this?
Thanks!
button.userInteractionEnabled = YES; I believe is the answer.
One solution might be that you create image of same as bar button item and assign to UIButton as background image, this will solve your issue.
Hope this helps you....
Solved it!
I added another UIView to the UIBarButtonItem and then I added the UIButton to the UIView.
I added a touch gesture to the UIView (And also kept the original touch event of the UIButton) that expanded the area that you can touch the button which solved the problem.

How to open a view with a button clicked as default

In my app i want to open a view with the content of a particular button (so that button should look clicked and should be not clickable). I have 4 button with pictures and all the four have different content inside them (Table view with different content).When this view gets open i want the first button clicked automatically and the content of that button should get displayed and by clicking any other button the content of that button should get displayed and the previous clicked button should be available to click again.
I am using different pictures for clicked and unclicked button.
Thanks,
Maybe this will help you
- (void)didClickButton:(id)sender {
UIButton *optionButton = (UIButton *)sender;
if(lastSelectedButton.tag!= optionButton.tag) {
optionButton.selected = YES;
//According to your needs enable or disable the button's interaction
}
Here lastSelectedButton should be an instance variable.
What you're describing sounds like a segmented control. Essentially the segmented control works like buttons on a tape recorder (dating myself, I know.) When you press Play, it stays down and can't be pressed again until you press Stop or FF or Rew, etc. (Ok, Stop doesn't really work that way, but the rest of the buttons do)
Unfortunately, I don't believe you can use your own images in a UISegmentedControl, but fortunately there's an open-source version that should work for you: https://github.com/xhan/PlutoLand/blob/master/PLSegmentView.h
Once you have the control in place you can change the content of your main view depending on the value of the segmented control. You can handle that in the UIControlEventValueChanged event
Keep a single selector for all the buttons something like
[btn addTarget:self action:#selector(templateSelected:) forControlEvents:UIControlEventTouchUpInside];
and make use of the tag to carry any index to the selector
[btn setTag:integer];
and if you want to keep track of previously clicked button then keep a global (id) and assign the current button address to the that id.
And if you want the first button to be clicked on load then call the function melodramatically during initialization of the first button.
[self templateSelected:firstButton];

UIActionSheet Customization

Can we change the order in which the destructive button and Other buttons appear in an UIActionSheet. By default the destructive button (red colored) appears above other buttons, in my app I would like the other buttons to appear above the destructive button.
No Problem.
Just alloc and init a new UIActionSheet instance and add the buttons in your order (one after another) using –addButtonWithTitle:. This method returns you the index at which the button has been added to. You can then set the Index of the destructive button via -setDestructiveButtonIndex:.
You can make any button in the UIActionSheet as destruction button by using the UIActionSheet property destructiveButtonIndex like,
actionSheet.destructiveButtonIndex = 1;

several uibuttons to subclass

I have several custom uibuttons on my view. I want to create a toggle button which when pressed, it will loop through all the UIButtons and enable a background image for them.
What I have done is to use an image as a background, then created clickable parts of it using blank custom buttons. I want this toggle function to then show the buttons.
My plan is to create a subclassed UIButton for the "hidden" buttons. When the toggle button is pressed, the code should then set the background image for each of these buttons to a "reddot.png". That stays on the screen until the toggle button is pressed again - this then disables each sub classed uibuttons background image.
What's the best way to do this?
I would advise you to not subclass UIButton for two reasons. First, UIButton is actually a class-cluster, which makes subclassing rather difficult. Secondly, I don't think it is needed in your case.
Simply create all the buttons as custom buttons. You can customize their appearance using methods like [button setHidden:] and [button setBackgroundImage:forState:]. The toggle button could then simply by linked to an IBAction, which would apply the appropriate customizations to the other buttons.

How can I dynamically hide a button from a view?

I would like to dynamically hide a button in one of my views depending on a certain condition.
I tried adding some code to the view controller's -viewWillAppear method, to make the button hidden before displaying the actual view, but I still don't know how to do that.
I have a reference to the button through an IBOutlet, but I'm not sure how to move forward from here. For reference, this is a UIBarButtonItem instance.
If you're trying to hide a UIBarButtonItem, you'll actually have to modify the contents of the parent bar. If it's a UIToolBar, you'll need to set the bar's items array to an array that doesn't include your item.
NSMutableArray *items = [[myToolbar.items mutableCopy] autorelease];
[items removeObject: myButton];
myToolbar.items = items;
Set the bar item to nil.
For example:
self.navigationItem.leftBarButtonItem = nil;
So I tried Ben's winning approach but in the end I found it to be wrong for my purposes - though I'm sure it depends upon what you're trying to do. I was trying to show a nav bar button under certain conditions only and then hide it as soon as the condition was no longer met (in my case it's a "Done" button used to hide the keyboard associated with a UITextView. It should only be displayed when the user is typing in the text view). My steps were as follows:
I added a UIBarButtonItem as a
property in my UIViewController
class. I instantiate it in the
initWithNibName method.
I assigned the UIBarButtonItem property as the
rightBarButtonItem in the nav bar as
soon as the user starts typing in
the text view.
I set the UIBarButtonItem property
to nil when the user is done typing.
It's working like a charm. I'm adding some code samples below.
First to instantiate the button in my view controller init method:
barButtonItemDone = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:#selector(done:)];
Then I set it as the right bar button in the delegate method that is called as soon as the user starts to edit the text view:
self.navigationItem.rightBarButtonItem=[self barButtonItemDone];
Finally, when the button itself is clicked, a method called "done" is called and I just set the rightBarButtonItem to nil inside that method:
self.navigationItem.rightBarButtonItem=nil;
If all that one is trying to hide is the back button in the navigation bar, there is an easier way:
self.navigationItem.hidesBackButton = YES;
Quote from developer documentation:
hidesBackButton
A Boolean value that determines whether the back button is hidden.
#property(nonatomic, assign) BOOL hidesBackButton
Discussion
YES if the back button is hidden when this navigation item is the top
item; otherwise, NO. The default value
is NO.
Availability
Available in iPhone OS 2.0 and later.
This is a bit of a hack, but it works in my case (and it properly handles dynamic spacing):
To hide:
myButton.width = 0.1;
To show:
myButton.width = 0.0;
A width of 0.0 is "auto width", and with a width of 0.1, the button totally disappears (not even a "sliver" of a button, though I haven't tried this on a retina display).
Another hacky solution:
myButton.customView = [[UIView alloc] init];
The best solution to this is less technical. All you need to do is create your normal navigation bar (top) or toolbar (bottom), but without the optional button. Then create another identical, but shorter bar which you then place at the part you want the optional button and create your optional button on this second shorter bar.
Now you can call hidden = YES on the whole additional bar.
The bars seamlessly overlap for me, your mileage may vary.
This answer is regarding text-based UIBarButtonItems, however, the same concept could be applied to other types of buttons as well. Note that this will allow one to both hide and show the item again. Many of the answers above (those setting the button's value to nil, for example, do not allow the button to be re-shown if that's desired).
TL;DR:
if (shouldShowMyBarButtonItem) {
self.myBarButtonItem.title = nil;
self.myBarButtonItem.action = nil;
} else if (!shouldShowMyBarButtonItem) {
self.myBarButtonItem.title = #"Title";
self.myBarButtonItem.action = #selector(mySelector:);
}
The long version:
The UIBarButtonItem I was trying to hide is in a UIToolbar, not a UINavigationBar so all the suggestions that access the left (or right) barButtonItem properties on the navigation item don't work for me. Also, as stated above, I wished to re-show the button when circumstances change.
Michael's suggestion came closest to working, however, with iOS 7 at least, there was still a very small sliver of the button displayed that was tappable. In my app, tapping the item when it's not supposed to be available was unacceptable. The above code both hides and, crucially, deactivates the button.
I call the above code in a private refresh method, which is called when a user event occurs.
This is what I did for button items that weren't part of the navigation bar (where Blank.png is a blank image I created that's the same size of the image it replaces):
theButton.enabled = NO;
theButton.image = [UIImage imageNamed: #"Blank.png"];
Ben's answer is technically correct, though when I try it on my custom UIToolbar, the items space out in a way that I don't like, because I use UIBarButtonSystemItemFlexibleSpace items.
If you want your other items to stay in the same place, you'll either have to set your flexible spaces to fixed spaces, or try what I did:
[filterBarButton.customView setHidden:YES];
note: this only works if your UIBarButtonItem uses custom views.
If you add a UIButton to the UIBarButtonItem rather than just use the UIBarButtonItem.
You can then assign UIButton.hidden to TRUE or YES and it (and the UIBarButtonItem) will not be visible or active.
Hope that helps.
Just set the button's hidden property to true:
myButton.hidden = YES;