It tells the compiler that any variable marked by it must be treated in a special way when it is used inside a block. Normally, variables and their contents that are also used in blocks are copied, thus any modification done to these variables don’t show outside the block. When they are marked with __block, … Read more
While the UITextField class has no max length property, it’s relatively simple to get this functionality by setting the text field’s delegate and implementing the following delegate method: Objective-C – (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string { // Prevent crashing undo bug – see note below. if(range.length + range.location > textField.text.length) { return NO; } NSUInteger … Read more
In Cocoa for Mac OS X, you have the next responder chain, where you can ask the text field what control should have focus next. This is what makes tabbing between text fields work. But since iOS devices do not have a keyboard, only touch, this concept has not survived the transition to Cocoa Touch. … Read more
Typically, Objective-C class are abstract by convention only—if the author documents a class as abstract, just don’t use it without subclassing it. There is no compile-time enforcement that prevents instantiation of an abstract class, however. In fact, there is nothing to stop a user from providing implementations of abstract methods via a category (i.e. at … Read more
Set the contentHorizontalAlignment: // Swift emailBtn.contentHorizontalAlignment = .left; // Objective-C emailBtn.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft; You might also want to adjust the content left inset otherwise the text will touch the left border: // Swift 3 and up: emailBtn.contentEdgeInsets = UIEdgeInsets(top: 0, left: 10, bottom: 0, right: 0); // Objective-C emailBtn.contentEdgeInsets = UIEdgeInsetsMake(0, 10, 0, 0);
For iOS 13: Use the .shadowColor property If this property is nil or contains the clear color, the bar displays no shadow For instance: let navigationBar = navigationController?.navigationBar let navigationBarAppearance = UINavigationBarAppearance() navigationBarAppearance.shadowColor = .clear navigationBar?.scrollEdgeAppearance = navigationBarAppearance For iOS 12 and below: To do this, you should set a custom shadow image. But for … Read more
Restrictions If you could send an SMS within a program on the iPhone, you’ll be able to write games that spam people in the background. I’m sure you really want to have spams from your friends, “Try out this new game! It roxxers my boxxers, and yours will be too! roxxersboxxers.com!!!! If you sign up … Read more
Here’s one: UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom]; [button addTarget:self action:@selector(aMethod:) forControlEvents:UIControlEventTouchUpInside]; [button setTitle:@”Show View” forState:UIControlStateNormal]; button.frame = CGRectMake(80.0, 210.0, 160.0, 40.0); [view addSubview:button];
WARNING, OUTDATED ANSWER: this answer is not up to date as per WWDC 2015, for the correct answer refer to the accepted answer (Daniel Hall) above. This answer will stay for record. Summarized from the developer library: From a practical perspective, in iOS and OS X outlets should be defined as declared properties. Outlets should … Read more
@synthesize will generate getter and setter methods for your property. @dynamic just tells the compiler that the getter and setter methods are implemented not by the class itself but somewhere else (like the superclass or will be provided at runtime). Uses for @dynamic are e.g. with subclasses of NSManagedObject (CoreData) or when you want to … Read more