I have tried with setting properties of UIPicker as SetHidden:False and SetVisible:NO , but they are still visible.
Hmmm, you should use "setHidden", not "setVisible" and you should use "YES", not "False" or "NO", so try "setHidden:YES", it should work if the UIPicker is correctly connected in Interface Builder.
And please copy the code directly from XCode instead of retyping it. It is "setHidden" with a small "s" and not with a capital "S".
Have you created an IBOutlet and set the link up for the referencing outlet?
[picker setHidden:YES];
Or picker.hidden = YES;
Don't forget that if you had dragged & dropped a UIDatePicker object onto your view using Interface Builder, you must link your object to the defined variable. You can do that by holding the CTRL button while dragging from your UIDatePicker object on your view to the File's Owner. I actually forget to do that more often than not. I end up programmatically creating my objects and adding them as subviews as a result.
Related
First, I am super-new to Objective-C/iOS development and, in fact, this question is for my first, test project. Also, I come from a C#/WinForms background so I'm coming into iOS development with certain pre-conceived notions of user interface design and application state. Please bear with me and help clear up my confusion.
I just created my first iOS application project which, consists of a Single View. I allowed Xcode to create all the files for me through the Single View project wizard. When it was finished, I opened my new applications, single UIView Nib file in the designer and I dropped three sliders onto the view.
The desired purpose of this application is very simple-- each slider corresponds to either the R, G or B values associated with the background color of my view.
I have figured out how to set the background of my view but I can not figure out how to access the values of each slider objects. Yes, I can hook-up and respond to an IBAction for each slider, but my plan is that each time a slider's value changes, I want the IBAction to call a refactored method that accesses the values of all three sliders and then set's the views Background Color based of the values associated with each one.
How can I access the values of my sliders? Specifically, how can I access the value of the sliders that I created by dragging and dropping them into the Nib designer window? I've seen code explaining how to programatically add a UISlider to your UIView and then access the value, but how do you access the value of a UISlider that's added to the Nib and, I assume, will be automatically "wired" in at compile time?
Hopefully this makes since? If I'm missing an intermediate step or critical concept, please let me know.
You create UISlider ivars/properties and make them IBOutlets:
#property (nonatomic, retain) IBOutlet UISlider* yourSlider;
You synthesize it in your .m file and the connect the IBOutlet in interface builder. The yourSlider pointer is then a reference to the object you connected it to. Note that it will only be loaded with the view of the UIViewController and therefore will be nil until viewDidLoad is called. You also must set it back to nil
self.yourSlider = nil;
in your viewDidUnload method (so that it is released). In Xcode 4 you have a convenient way of doing all the above steps in one action (see the "Interface Builder is Built-in" of What's new in XCode 4)
Similar to CTRL+dragging from the UISlider to the .m file to create the IBAction, you can CTRL+drag the UISlider from your .nib designer to the associated .h file and have it create a property for you. Then, from your .m file, you can access self.mySlider (or whatever you name the property).
There's a video on this page that shows binding to a UISlider specifically.
Another approach is to use the tag property of a view.
#property(nonatomic) NSInteger tag
- (UIView *)viewWithTag:(NSInteger)tag
You can set the tag property of a view in the interface builder and later reference that view in your controller.
UIView *myViewFromTag = [self.view viewWithTag:theNumberYouSetInIB];
In general, it's better to stick with IBOutlets. However, there are certain situations where it makes more sense to use tags.
Good luck!
probably a very simple question but can't find the right answer anywhere. I am using XCode 4 and working on an iphone app, which probably sums up all the info that I need to provide.
Here it is:
- I created a ViewBasedApplication
- At some point depending on the user input, I load a TableView
But now how on Earth do I add a button or something to return? Note: I can't use a NavigationBased app, that would be easier but would not work for me.
Help anyone?
If you used a UITableViewController, you may want to use a UIViewController instead. In the UIVeiwController, you can add a UITableView along with your own UINavigationBar or, if you don't want to use a UINavigationBar, you could leave room for some type of custom UIButton. Either the UINavigationBar button or your custom UIButton action could trigger a close of your UIViewController.
If you add the UIViewController as a subview, then Cyprian's [self removeFromSuperView]; would work. If you present as a modal as Jamie suggests, you could use [self dismissModalViewControllerAnimated:YES];.
Well I don't know you code but you could always call
[self removeFromSuperView];
I have a UIToolbar, and then add two UIBarButtonItem to items of UIToolbar. How can I change the color of UIBarButtomItem? I did't find a API in the document.
see "Changing colors of UINavigationBarButtons"
EDIT: I remove the link because the domain is down...
The is the text from google cache:
Alright, here’s another quick tip. “How to change the colors of a button on a toolbar.” Of course, this can be applied to any toolbar but I am going to demonstrate the procedure on a UINavigationBar.
The above image only shows a couple of colors. In truth, you can make the button any color that you want. Fantastic! The code is really simple to do this as well. The first thing that we want to do is open the header file for whichever object will be turning a nav bar button a different color and declare the forward class UINavigationButton. You can get this class by either iterating through the subviews of the UINavigationBar, reading its subviews class names, or by class-dumping UIKit if you have a jailbroken device.
Place the following line before your interface declaration:
#class UINavigationButton;
Now, declare a new method in the header that we will use to actually change the button’s color.
- (void)changeNavigationButtonColorToColor:(UIColor *)newColor
Or something similar to the above line of code.
Now, open up your object’s implementation file and implement the above method. Anywhere in your file, add the following method:
- (void)changeNavigationButtonColorToColor:(UIColor *)newColor {
for (UIView *view in self.navigationController.navigationBar.subviews) {
NSLog(#"%#", [[view class] description]);
if ([[[view class] description] isEqualToString:#"UINavigationButton"]) {
[(UINavigationButton *)view setTintColor:newColor];
}
}
}
As you can see above, this is actually a lot easier than it first appears to be. What we first do is set up a for loop to iterate through the subviews of the UINavigationBar using NSFastEnumeration. We then output the class name of the subview, for future reference. IF the class name is UINavigationButton, then we’ve got our view. All we do is set the tintColor property if the UINavigationButton.
That’s it, we’re done!
Alternatively, if you want a wider scope, I’d suggest creating a new UINavigationBar category and placing the button color changing method in there. This was your method can be performed by any class that uses a UINavigationBar without having to recreate the same method over and over.
Remember, a back button and a navigation button are not the same thing. You will have to color the back button separately.
And as usual, here’s a link to a sample app that demonstrates this code: NavButtonColor.zip
UIBarButtomItem has limitation in customization so you can use UIButton in place of UIBarButtonItem it will gives you more customization.
For a solution that doesn't use a private API.
You can fake it by making a UISegmentedControl look like a UIBarButtonItem.
http://fredandrandall.com/blog/2011/03/31/how-to-change-the-color-of-a-uibarbuttonitem/
I'm contemplating writing some helper functions to make it easier to do simple changes to the UI elements in my iPhone NIB. Mainly - I want to access a UILabel, or other element, via its Name in Interface Builder. Is this possible? Is there a smarter approach?
Example
Say I want to make a super simple iPhone app that displays 'Hello World'. I start a new project and then open the NIB and drag a UILabel into my view and give it a 'Name' of 'LblMain'. Now, presuming that I've included my handy helper function, I'd like to assign the label some new text something like this:
[helper setText:#"Hello World" forLabel:#"LblMain"];
-or-
UILabel *ObjTmp = [helper getUILabel:#"LblMain"];
ObjTemp.text = #"Hello World";
Now - the trick is that I didn't add a:
IBoutlet UILabel *ObjLblMain;
anywhere in .h file - I'm just accessing that label dynamically - wouldn't that be nice?!
Now, for simple apps, to add some more labels or images, I could drag them into my NIB, assign them names in that element's inspector window, and then immediately access them inside code without the stuttering & hassle of adding them in the .h file.
Motivation
Basically, I'm frustrated that I have to wire every element in my NIB - it's a lot of stuttering and bookkeeping that I'd rather avoid.
I could give a design some naming conventions, and they could generate a NIB without needing to be intimate with the implementation.
Name is 100% not accessible after the object is loaded, something I always thought was odd too.
What is accessible is "tag", if you really want to access an element without defining an outlet you can set the (integer only) "tag" value, and then within the superview that holds the tagged element call viewWithTag: passing in the same integer. Don't forget the default is "0" so use something else.
You can definitely load the NIB programmatically, find all the objects and query them to work out what points to what. Just look at Loading Nib Files Programmatically. But the problem is that the Interface Builder Identity Name isn't exposed outside of IB. So I'm not sure what you would use as the "forLabel" parameter. The "Name" field is just a convenience for the IB document window. It's not a property on NSObject.
It can be done by the element tag:
Lets say you have UIView xib file called "yourView" and inside it there is UILabel that you want to access it without wiring.
Set a tag to the UILabel in "yourView" xib file, lets assume you set UILabel tag to 100.
After loading "yourView" anywhere you can get UILabel without having any wiring by using this code.
UILabel* yourlabel =(UILabel*) [yourView viewWithTag: 100];
//do whatever you want to your label.
I think you can try opening the xib in some external editor as XML and see how the compiler sees it, then you might possibly do the same way
For iOS6+ you can use restorationId instead of tag, to make it more "readable", for example you can set the same name in your nib file and in restoration id.
If you do not want to link all the outlets from your nib to your viewcontroller, you still can access them by searching in your current view subviews tree. Note that subviews arrangement is a tree (the same tree that you can see in your nib file), so you will need to do some recursion if you have nested views.
For example:
UIButton *nibButtonView = nil;
for (UIView *view in [self.view subviews]){
if ([view.restorationIdentifier isEqualToString:#"myNibButtonView"]){
nibButtonView = (UIButton *)view;
}
}
[nibButtonView setTitle:#"Yeah" forState:UIControlStateNormal];
In your nib file you should have a button with a restorationId equals to "myNibButtonView", you can find the restorationId textfield in your identity inspector (third column of utilities)
You may use this if you have a huge number of outlets a you don't want to linked them all.
I have a UILabel Outlet, and everytime I access its text property with multiple characters, then it will crash and gives me EXC_BAD_ACCESS. Its very weird and I can't find any solution for this issue.
Thanks.
sasayins
When it got EXC _BAD _ACCESS, would you mind get the backtrace and post it here?
Or better: post the code where you access/modify the UILabel.
Did you synthesize the property? are you releasing it somewhere by mistake? gotta put some code up in order for us to help you...
You probably forgot to link the outlet in Interface Builder to the desired UILabel. This means that the UILabel is currently nil (non existent). Drag a line from the file owner to the UILabel to connect the outlet in Interface Builder.
Make sure that your outlet does not have the same name as a property of one of the super classes of your view controller. For example, UIViewController has a title property, and if you create an outlet with the name of "title" you are overriding this property and will most likely have problems.