All Questions

1100
votes
35answers
382919 views

Passing Data between View Controllers

I'm new to iOS and, Objective-C and the whole MVC paradigm and I'm stuck with the following: I have a view that acts as a data entry form and I want to give the user the option to select multiple pro...
838
votes
63answers
626247 views

What does this mean? "'NSUnknownKeyException', reason: … this class is not key value coding-compliant for the key X"

I'm trying to link a UILabel with an IBOutlet created in my class. My application is crashing with the following error. What does this mean? How can I fix it? *** Terminating app due to uncaught ...
1225
votes
21answers
418448 views

Using Auto Layout in UITableView for dynamic cell layouts & variable row heights

How do you use Auto Layout within UITableViewCells in a table view to let each cell's content and subviews determine the row height (itself/automatically), while maintaining smooth scrolling performan...
503
votes
5answers
200158 views

What are Unwind segues for and how do you use them?

iOS 6 and Xcode 4.5 has a new feature referred to as "Unwind Segue": Unwind segues can allow transitioning to existing instances of scenes in a storyboard In addition to this brief entry in Xcod...
1440
votes
84answers
557286 views

How to make a UITextField move up when keyboard is present?

With the iPhone SDK: I have a UIView with UITextFields that brings up a keyboard. I need it to be able to: Allow scrolling of the contents of the UIScrollView to see the other text fields once the...
1146
votes
36answers
383334 views

How to check for an active Internet connection on iOS or OSX?

I would like to check to see if I have an Internet connection on iOS using the Cocoa Touch libraries or on OSX using the Cocoa libraries. I came up with a way to do this using an NSURL. The way I did...
1126
votes
23answers
517001 views

Transport security has blocked a cleartext HTTP

What setting do I need to put in my info.plist to enable HTTP mode as per the following error message? Transport security has blocked a cleartext HTTP (http://) resource load since it is insecur...
1096
votes
22answers
419616 views

How to 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, let's say they are 'Person' objects. I want to sort the NSMutableArray by Person.bi...
657
votes
18answers
295898 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?
46
votes
1answers
8523 views

Speed up fetching posts for my social network app by using query instead of observing a single event repeatedly

I have an array of keys which lead to post objects for my social network like so /posts/id/(post info) When I load the posts I load /posts/0 and then /posts/1 etc using the observeSingleEventOfType(...

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