iOS cheat sheet

Sizes

Screen size

[[UIScreen mainScreen] bounds];

Application Frame = ScreenSize - Status bar

[[UIScreen mainScreen] applicationFrame];

Keyboard

Keyboard show and hide events

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillShow:) name:UIKeyboardDidShowNotification object:nil];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(keyboardWillHide:) name:UIKeyboardWillHideNotification object:nil];

Format a date

static NSDateFormatter* dateFormatter = nil;
if(dateFormatter == nil){
    dateFormatter = [[NSDateFormatter alloc] init];
    dateFormatter.dateFormat = @"yyyy-MM-dd";
}
NSDate *date = ...
NSString *dateStr = [dateFormatter stringFromDate:date];