•
AppDelegate object can access from any class in the same application like below. Methods or properties shared between controllers can be defined under application delegates. SomeAppDelegate *appDelegate = (SomeAppDelegate *)[[UIApplication sharedApplication] delegate];
•
Use NSSearchPathForDirectoriesInDomains(). First argument “NSDocumentDirecotry” is the key to specify special directory, in this case Document directory under the application. The method returns absolute path expression. NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; NSLog(@”NSDocumentDirectory is %@”, documentsDirectory);
•
Apparently a UIColor is not necessarily a single color, but can be a pattern as well. Confusingly, this is not supported in Interface Builder. Instead you set the backgroundColor of the view (say, in -viewDidLoad) with the convenience method +colorWithPatternImage: and pass it a UI Image. For Instance:
•
Animation can be applied while its frame, bounds, center, transform, alpha… is being changed. The key is set start and end values between beginAnimations and commitAnimations, so called animation block.
•
UIAlertView takes care of this UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@”Alert View” message:@”Here is an alert message” delegate:nil cancelButtonTitle:@”Cancel” otherButtonTitles:@”OK”, nil]; [alert show]; // Since alert object is allocated above, it must be released here [alert release];