Category: Objective-C

Formatting dates in cellForRowAtIndexPath or another method that gets called very often will make an app noticeably slower if an NSDateFormatter needs to be initialized on every call. Storing the NSDateFormatter in a property or making it static are both fine options but if it’s around anyway it might as well be used by the… Continue reading Sharing a single NSDateFormatter instance

CGRectIntegral is a function for rounding all the values of a CGRect at once, typically used for snapping frames to pixels. For a good example of how this helps prevent image blurring and other related rendering issues see this stackoverflow answer. On retina screens CGRectIntegral still rounds to the nearest point (1.0) rather than the… Continue reading Retina alterative to CGRectIntegral

Sometime you need to know if a UITableViewCell is completely visible and for those times there’s this handy UITableViewCell category. //Place in UITableViewCell Category – (BOOL) isCompletelyVisible { // For parents category see pdenya.com/g/uiview_parents UITableView *tableview = (UITableView *)[self parents:[UITableView class]]; CGRect rect = [tableview rectForRowAtIndexPath:[tableview indexPathForCell:self]]; rect = [tableview convertRect:rect toView:tableview.superview]; BOOL completelyVisible =… Continue reading Checking if a UITableViewCell is fully visible

Whenever you have a modal element that outside touches should cancel a few things need to happen: Touches inside the modal element should behave normally Outside touches should not trigger touch events on tappable elements Outside touches should trigger a handler to close the modal In my case I was swiping a UITableViewCell and revealing… Continue reading Tap anywhere else to cancel in Objective C

Here’s an if chain that figures out the relative time. The current version suites my needs but it’s easy to modify. //print date to countdown_label NSCalendar *calendar = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease]; NSDate *fromDate = [NSDate date]; NSDate *toDate = [user filtered_until]; NSDateComponents *components = [calendar components:NSDayCalendarUnit|NSHourCalendarUnit|NSMinuteCalendarUnit fromDate:fromDate toDate:toDate options:0]; NSString *countdown_text = @””; if… Continue reading Custom Relative Time with Date Components

If you have, for example, a child view of a UITableViewCell and you need to get the UITableViewCell in question you can quickly do something like: UITableViewCell *cell = (UITableViewCell *)the_view.superview.superview; It works but this code is fragile because it requires that the view heirarchy not change (also things like this usually point to a… Continue reading Getting a particular superview in Objective-C