39,634 questions
1412
votes
39
answers
517k
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 ...
- 47.3k
1331
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', ...
1048
votes
14
answers
449k
views
Constants in Objective-C
I'm developing a Cocoa application, and I'm using constant NSStrings as ways to store key names for my preferences.
I understand this is a good idea because it allows easy changing of keys if ...
- 20.4k
776
votes
20
answers
387k
views
How do I create delegates in Objective-C?
I know how delegates work, and I know how I can use them.
But how do I create them?
- 15.2k
729
votes
10
answers
270k
views
Cocoa Autolayout: content hugging vs content compression resistance priority
I can't find a clear answer on Apple documentation regarding Cocoa Autolayout about the difference between content hugging and compression resistance.
Can somebody explain their usages and ...
- 9,132
718
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 ...
- 50.6k
660
votes
9
answers
181k
views
What does the NS prefix mean?
Many classes in Cocoa/Cocoa Touch have the NS prefix. What does it mean?
- 21.4k
634
votes
14
answers
231k
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?
- 26.3k
572
votes
8
answers
166k
views
@synthesize vs @dynamic, what are the differences?
What are the differences between implementing a @property with @dynamic or @synthesize?
- 9,716
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 ...
- 33.5k
427
votes
13
answers
147k
views
throwing an exception in objective-c/cocoa
What's the best way to throw an exception in objective-c/cocoa?
- 9,423
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);
...
- 5,879
394
votes
9
answers
209k
views
How do I convert NSMutableArray to NSArray?
How do I convert NSMutableArray to NSArray in objective-c?
- 4,223
363
votes
25
answers
51k
views
Exception thrown in NSOrderedSet generated accessors
On my Lion app, I have this data model:
The relationship subitems inside Item is ordered.
Xcode 4.1 (build 4B110) has created for me the file Item.h, Item.m, SubItem.h and SubItem.h.
Here is the ...
- 7,046
363
votes
12
answers
190k
views
Best way to define private methods for a class in Objective-C
I just started programming Objective-C and, having a background in Java, wonder how people writing Objective-C programs deal with private methods.
I understand there may be several conventions and ...