Since Xcode 5 and iOS 7 the default appearance of a UINavigationBar is black translucent. This even affects the same app running in iOS 6. Black opaque is deprecated and can no longer be set in Interface Builder.
However, you can set the appearance for all nav bars by putting this little gem in your App Delegate’s didFinishLaunchingWithOptions method:
Note that iOS 7 devices are affected differently by this change: only the icon/text colour will change into your specified colour, but the bar itself will remain translucent. Using black means text buttons are barely readable. Hence, a version check would be appropriate:
// changes the colour of all navigation bars on iOS 6 and lower
You can hide (and show) navigation bars and toolbars from your UINavigationController with extremely funky animations, much like we see in the Photos app on iOS. In the app, when you single-tap the screen, both top and bottom toolbars disappear.
Here’s how we do that: Provided you have your view controller embedded in a UINavigationController, you can call the following methods to slide the top and bottom bars in and out:
Some things are really easy to do via a Storyboard – but when you want to create the same thing in code I frequently forget how to do it.
Turns out it’s equally simple: this example assumes you have a View Controller which is embedded in a Navigation Controller (so it already has a UINavigationBar at the top). Here’s how you add a button to it, set the title and target, and tell it what to do when it’s pressed:
// first we create a button and set it's properties
If the App Delegate has something that your top view controller needs then you simply pass it the required object via a property set on the top view controller. This is easy when your top view controller is also the root view controller.
However, when you embed your top view controller in a Navigation Controller, and perhaps that one is also embedded in a Tab Bar Controller, then this array isn’t quite so easy to figure out (and I must admit that I always forget how to do this when a new challenge arises).
So here’s how this works. In this example, the thing that’s displayed is called MyViewController, which is embedded in a Navigation Controller. I’m passing it the App Delegate’s self.managedObjectContext which is defined as a property on MyViewController.
First we access the array of all view controllers and count it. We subtract one (because arrays are 0 based), and another one to go back in history – hence we go “minus 2″. Then we pop to view controller just behind the current one.
Test if the returned value is less than zero though…
If you want to go back all the way to the root view controller, there’s a method for that:
The back button (and its text) is only displayed in the NEXT view controller on the stack. So changing the back button in the detail view controller for example doesn’t change what’s displayed when the detail view controller is displayed. You must change it one step earlier, in the master controller’s navigation bar.
Here’s an example. MyNavController is the class for the Navigation Controller. This snipped is called from any View Controller in sequence and assumes we have an integer myNumber which is increased by one: