If you use the underscore prefix for your ivars (which is nothing more than a common convention, but a useful one), then you need to do 1 extra thing so the auto-generated accessor (for the property) knows which ivar to use. Specifically, in your implementation file, your synthesize should look like this: @synthesize missionName = … Read more
I solved this by adding a category to NSMutableArray. Edit: Removed unnecessary method thanks to answer by Ladd. Edit: Changed (arc4random() % nElements) to arc4random_uniform(nElements) thanks to answer by Gregory Goltsov and comments by miho and blahdiblah Edit: Loop improvement, thanks to comment by Ron Edit: Added check that array is not empty, thanks to … Read more
NSDate objects don’t have time zones. They represent an absolute moment in time. However, when you ask one for its description (by printing it with NSLog(), e.g.), it has to pick a time zone. The most reasonable “default” choice is GMT. If you’re not in GMT yourself, the date will seem to be incorrect, by … Read more
FYI, I combined Keremk’s answer with my original outline, cleaned-up the typos, generalized it to return an array of colors and got the whole thing to compile. Here is the result: + (NSArray*)getRGBAsFromImage:(UIImage*)image atX:(int)x andY:(int)y count:(int)count { NSMutableArray *result = [NSMutableArray arrayWithCapacity:count]; // First get the image into your data buffer CGImageRef imageRef = [image … Read more
An Objective-C delegate is an object that has been assigned to the delegate property another object. To create one, you define a class that implements the delegate methods you’re interested in, and mark that class as implementing the delegate protocol. For example, suppose you have a UIWebView. If you’d like to implement its delegate’s webViewDidStartLoad: … Read more
How can I check for an active Internet connection on iOS or macOS?
Xcode – How to fix ‘NSUnknownKeyException’, reason: … this class is not key value coding-compliant for the key X” error?
Firstly, before you subclass an object, you should ask yourself “do I need to do this?”. Subclassing is a more complex way of interacting and extending the functionality of other classes, so you should make sure that what you are trying to achieve cannot easily be achieved through another, simpler method, such as delegation, notifications … Read more