Questions tagged [cocoa-touch]
The Cocoa Touch Frameworks that drive iOS apps share many proven patterns found on the Mac, but were built with a special focus on touch-based interfaces and optimization.
cocoa-touch
34,527
questions
2340
votes
51
answers
764k
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Vertically align text to top within a UILabel
I have a UILabel with space for two lines of text. Sometimes, when the text is too short, this text is displayed in the vertical center of the label.
How do I vertically align the text to always be ...
- 28.9k
1406
votes
39
answers
512k
views
How can I check for an active Internet connection on iOS or macOS?
I would like to check to see if I have an Internet connection on iOS using the Cocoa Touch libraries or on macOS using the Cocoa libraries.
I came up with a way to do this using an NSURL. The way I ...
- 46.9k
1325
votes
27
answers
486k
views
How do I sort an NSMutableArray with custom objects in it?
What I want to do seems pretty simple, but I can't find any answers on the web. I have an NSMutableArray of objects, and let's say they are 'Person' objects. I want to sort the NSMutableArray by ...
- 45k
1322
votes
82
answers
1.0m
views
Xcode - How to fix 'NSUnknownKeyException', Reason: "… this class is not key value coding-compliant for the key X" error?
I'm trying to link a UILabel with an IBOutlet created in my class.
My application is crashing with the following error"
***
Terminating app due to uncaught exception
'NSUnknownKeyException', ...
1278
votes
42
answers
540k
views
How can I disable the UITableView selection?
When you tap a row in a UITableView, the row is highlighted and selected. Is it possible to disable this so tapping a row does nothing?
- 39k
819
votes
33
answers
296k
views
Loaded nib but the 'view' outlet was not set
I added a new nib file to my project, and tried to load it.
However, when I click on the toolbar icon that is supposed to take me to the view that I created, I get an NSInternalInconsistencyException ...
- 10.9k
792
votes
32
answers
241k
views
Can I embed a custom font in an iPhone application?
I would like to have an app include a custom font for rendering text, load it, and then use it with standard UIKit elements like UILabel. Is this possible?
- 32.5k
771
votes
34
answers
200k
views
Eliminate extra separators below UITableView
When I set up a table view with 4 rows, there are still extra separators lines (or extra blank cells) below the filled rows.
How would I remove these cells?
- 9,851
754
votes
63
answers
392k
views
Placeholder in UITextView
My application uses an UITextView. Now I want the UITextView to have a placeholder similar to the one you can set for an UITextField.
How to do this?
719
votes
16
answers
172k
views
@class vs. #import
It is to my understanding that one should use a forward-class declaration in the event ClassA needs to include a ClassB header, and ClassB needs to include a ClassA header to avoid any circular ...
- 49.5k
671
votes
38
answers
438k
views
Attempt to present UIViewController on UIViewController whose view is not in the window hierarchy
Just started using Xcode 4.5 and I got this error in the console:
Warning: Attempt to present < finishViewController: 0x1e56e0a0 > on < ViewController: 0x1ec3e000> whose view is not in the ...
- 10.9k
656
votes
9
answers
177k
views
What does the NS prefix mean?
Many classes in Cocoa/Cocoa Touch have the NS prefix. What does it mean?
- 21.2k
633
votes
14
answers
229k
views
Cocoa: What's the difference between the frame and the bounds?
UIView and its subclasses all have the properties frame and bounds. What's the difference?
- 26.1k
614
votes
21
answers
396k
views
Giving UIView rounded corners
My login view has a subview which has a UIActivityView and a UILabel saying "Signing In…". This subview has corners which aren't rounded. How can I make them round?
Is there any way to do it inside ...
- 24.8k
585
votes
50
answers
325k
views
How can I create a UIColor from a hex string?
How can I create a UIColor from a hexadecimal string format, such as #00FF00?
- 7,906
582
votes
19
answers
295k
views
UITableViewCell, show delete button on swipe
How do I get the delete button to show when swiping on a UITableViewCell? The event is never raised and the delete button never appears.
- 19.4k
575
votes
11
answers
131k
views
Should IBOutlets be strong or weak under ARC?
I am developing exclusively for iOS 5 using ARC. Should IBOutlets to UIViews (and subclasses) be strong or weak?
The following:
@property (nonatomic, weak) IBOutlet UIButton *button;
Would get rid ...
- 15.4k
572
votes
8
answers
165k
views
@synthesize vs @dynamic, what are the differences?
What are the differences between implementing a @property with @dynamic or @synthesize?
- 9,708
571
votes
34
answers
567k
views
How do I create a basic UIButton programmatically?
How can I create a basic UIButton programmatically? For example in my view controller, when executing the viewDidLoad method, three UIButtons will be created dynamically and its layout or properties ...
- 15.9k
570
votes
24
answers
234k
views
How to lose margin/padding in UITextView
I have a UITextView in my iOS application, which displays a large amount of text.
I am then paging this text by using the offset margin parameter of the UITextView.
My problem is that the padding of ...
- 7,282
565
votes
41
answers
431k
views
How do I size a UITextView to its content?
Is there a good way to adjust the size of a UITextView to conform to its content? Say for instance I have a UITextView that contains one line of text:
"Hello world"
I then add another line of text:
...
- 10.1k
560
votes
36
answers
747k
views
How would I create a UIAlertView in Swift?
I have been working to create a UIAlertView in Swift, but for some reason I can't get the statement right because I'm getting this error:
Could not find an overload for 'init' that accepts the ...
- 7,579
552
votes
31
answers
400k
views
How to set cornerRadius for only top-left and top-right corner of a UIView?
Is there a way to set cornerRadius for only top-left and top-right corner of a UIView?
I tried the following, but it end up not seeing the view anymore.
UIView *view = [[UIView alloc] initWithFrame:...
- 14.5k
546
votes
18
answers
457k
views
How to get the screen width and height in iOS?
How can one get the dimensions of the screen in iOS?
Currently, I use:
lCurrentWidth = self.view.frame.size.width;
lCurrentHeight = self.view.frame.size.height;
in viewWillAppear: and ...
- 13.1k
546
votes
18
answers
307k
views
How to programmatically send SMS on the iPhone?
Does anybody know if it's possible, and how, to programmatically send a SMS from the iPhone, with the official SDK / Cocoa Touch?
Marco
523
votes
14
answers
241k
views
How can I set the title of a UIButton as left-aligned?
I need to display an email address on the left side of a UIButton, but it is being positioned to the centre.
Is there any way to set the alignment to the left side of a UIButton?
This is my current ...
- 8,790
493
votes
38
answers
281k
views
iOS - Dismiss keyboard when touching outside of UITextField
I'm wondering how to make the keyboard disappear when the user touches outside of a UITextField.
- 7,789
492
votes
46
answers
305k
views
Set the maximum character length of a UITextField
How can I set the maximum amount of characters in a UITextField on the iPhone SDK when I load up a UIView?
- 7,605
457
votes
33
answers
266k
views
Getting current device language in iOS?
I'd like to show the current language that the device UI is using. What code would I use?
I want this as an NSString in fully spelled out format. (Not @"en_US")
EDIT: For those driving on by, there ...
- 57.9k
452
votes
13
answers
147k
views
How to print out the method name and line number and conditionally disable NSLog?
I'm doing a presentation on debugging in Xcode and would like to get more information on using NSLog efficiently.
In particular, I have two questions:
is there a way to easily NSLog the current ...
- 33.3k
450
votes
36
answers
336k
views
UIView with rounded corners and drop shadow?
I’ve been working on an application for a couple of years and received a simple design request: Round the corners on a UIView and add a drop shadow.To do as given below.
I want a custom UIView... : I ...
- 6,259
444
votes
31
answers
229k
views
Text inset for UITextField?
I would like to inset the text of a UITextField.
Is this possible?
- 20.5k
425
votes
17
answers
395k
views
How to use background thread in swift?
How to use threading in swift?
dispatchOnMainThread:^{
NSLog(@"Block Executed On %s", dispatch_queue_get_label(dispatch_get_current_queue()));
}];
- 4,607
418
votes
9
answers
109k
views
Is It Possible to NSLog C Structs (Like CGRect or CGPoint)?
I want to be able to debug C structures without having to explicitly type every property that they consist of.
i.e. I want to be able to do something like this:
CGPoint cgPoint = CGPointMake(0,0);
...
- 5,869
415
votes
19
answers
379k
views
Set UIButton title UILabel font size programmatically
I need to set the font size of the title UILabel of a UIButton programmatically.
syam s
406
votes
21
answers
139k
views
Can you animate a height change on a UITableViewCell when selected?
I'm using a UITableView in my iPhone app, and I have a list of people that belong to a group. I would like it so that when the user clicks on a particular person (thus selecting the cell), the cell ...
Ted
394
votes
9
answers
208k
views
How do I convert NSMutableArray to NSArray?
How do I convert NSMutableArray to NSArray in objective-c?
- 4,223
391
votes
33
answers
208k
views
How do you add multi-line text to a UIButton?
I have the following code...
UILabel *buttonLabel = [[UILabel alloc] initWithFrame:targetButton.bounds];
buttonLabel.text = @"Long text string";
[targetButton addSubview:buttonLabel];
[targetButton ...
- 4,619
388
votes
7
answers
97k
views
UILongPressGestureRecognizer gets called twice when pressing down
I am detecting if the user has pressed down for 2 seconds:
UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]
initWithTarget:...
- 60.5k
383
votes
31
answers
212k
views
Easy way to dismiss keyboard?
I have quite a few controls scattered throughout many table cells in my table, and I was wondering if there's an easier way to dismiss the keyboard without having to loop through all my controls and ...
- 4,810
374
votes
4
answers
94k
views
How to write iOS app purely in C
I read here Learn C Before Objective-C?
Usually I then replace some Obj-C code with pure C code (after all you can mix them as much as you like, the content of an Obj-C method can be entirely, pure ...
- 64k
368
votes
30
answers
252k
views
How do I add 1 day to an NSDate?
Basically, as the title says. I'm wondering how I could add 1 day to an NSDate.
So if it were:
21st February 2011
It would become:
22nd February 2011
Or if it were:
31st December 2011
It would ...
- 16k
367
votes
24
answers
214k
views
How to use Auto Layout to move other views when a view is hidden?
I have designed my custom Cell in IB, subclassed it and connected my outlets to my custom class. I have three subviews in cell content which are: UIView (cdView) and two labels (titleLabel and ...
- 4,357
366
votes
28
answers
180k
views
Get the current first responder without using a private API
I submitted my app a little over a week ago and got the dreaded rejection email today. It tells me that my app cannot be accepted because I'm using a non-public API; specifically, it says,
The non-...
- 8,394
358
votes
16
answers
258k
views
How do I draw a shadow under a UIView?
I'm trying to draw a shadow under the bottom edge of a UIView in Cocoa Touch. I understand that I should use CGContextSetShadow() to draw the shadow, but the Quartz 2D programming guide is a little ...
- 4,642
357
votes
16
answers
60k
views
UITableView didSelectRowAtIndexPath: not being called on first tap
I'm having an issue with UITableView's didSelectRowAtIndexPath.
My table is setup so that when I select row it initializes a new view controller and pushes it.
The first time I tap any row in the ...
- 30.8k
352
votes
34
answers
279k
views
UITableView - change section header color
How can I change color of a section header in UITableView?
EDIT: The answer provided by DJ-S should be considered for iOS 6 and above. The accepted answer is out of date.
- 53.1k
349
votes
17
answers
346k
views
How to scale a UIImageView proportionally?
I have a UIImageView and the objective is to scale it down proportionally by giving it either a height or width.
UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL ...
- 18.3k
349
votes
20
answers
146k
views
iOS UIImagePickerController result image orientation after upload
I am testing my iPhone application on an iOS 3.1.3 iPhone. I am selecting/capturing an image using a UIImagePickerController:
UIImagePickerController *imagePicker = [[UIImagePickerController alloc] ...
- 26.2k
346
votes
33
answers
124k
views
What are best practices that you use when writing Objective-C and Cocoa? [closed]
I know about the HIG (which is quite handy!), but what programming practices do you use when writing Objective-C, and more specifically when using Cocoa (or CocoaTouch).