No, you do not need to check whether you’re already on the main thread. By dispatching the block to the main queue, you’re just scheduling the block to be executed serially on the main thread, which happens when the corresponding run loop is run. If you already are on the main thread, the behaviour is … Read more
I’m surprised at some of the solutions being suggested here. There’s really no need for dummy navigation controllers in your storyboard, hiding views & firing segues on viewDidAppear: or any other hacks. If you don’t have the storyboard configured in your plist file, you must create both the window and the root view controller yourself … Read more
In Xcode 6 you can do this in the storyboard:
If your object is myObject, and you want to test to see if it is an NSString, the code would be: [myObject isKindOfClass:[NSString class]] Likewise, if you wanted to test myObject for a UIImageView: [myObject isKindOfClass:[UIImageView class]]
The compiler is smarter than you. It sees @”Hello world” and thinks “Aha! A constant string!” It then sees [[NSString alloc] initWithString:@”Hello world!”] and thinks “Aha! An immutable object created with a constant string!” It then collapses both of them down into a single NSConstantString, which has a retainCount of UINT_MAX, so that it can … Read more
I haven’t used them myself, but you could try GCMathParser and DDMathParser.
For non-autolayout storyboards/NIBs, your code is fine. By the way, it’s now generally advised that you animate using blocks: [UIView animateWithDuration:3.0 animations:^{ self.logo.center = CGPointMake(self.logo.center.x, self.logo.center.y – 100.0); }]; Or, if you want a little more control over options and the like, you can use: [UIView animateWithDuration:3.0 delay:0.0 options:UIViewAnimationCurveEaseInOut animations:^{ self.logo.center = CGPointMake(self.logo.center.x, self.logo.center.y – … Read more
Fastest NSString category implementation that I could think of (cocktail of some examples): – (NSData *)dataFromHexString { const char *chars = [self UTF8String]; int i = 0, len = self.length; NSMutableData *data = [NSMutableData dataWithCapacity:len / 2]; char byteChars[3] = {‘\0′,’\0′,’\0’}; unsigned long wholeByte; while (i < len) { byteChars[0] = chars[i++]; byteChars[1] = chars[i++]; … Read more
Here’s how it works: There’s a class called NSXMLParser. It’s used to parse XML files. However, NSXMLParser is stupid. All it knows how to do is parse XML, but it doesn’t know what it’s supposed to do with the information it finds. Enter a delegate. A delegate is like a nanny. Since the XMLParser doesn’t … Read more
NSArray and NSMutableArray provide methods to filter array contents. NSArray provides filteredArrayUsingPredicate: which returns a new array containing objects in the receiver that match the specified predicate. NSMutableArray adds filterUsingPredicate: which evaluates the receiver’s content against the specified predicate and leaves only objects that match. These methods are illustrated in the following example. NSMutableArray *array … Read more