Tag: Programming

Safe area fix guide for earlier versions of iOS

Safe area layout is introduced in iOS11 but what can we do if we are supporting < iOS 11 and we have a xib view that is initiated in a ViewController and somehow the upper part of the xib view appears behind the NavigationBar??? To fix this, simply add this line in your viewDidLoad.

self.edgesForExtendedLayout = UIRectEdge.init(rawValue: 0)

For more information visit EdgesForExtendedLayout at Apple.

Embed a UIViewController in a UINavigationController Programmatically

We know how to embed a ViewController in a NavigationController in Storyboard. However, I came across a scenario where I had to initiate it programmatically. The code:

let viewController = MyViewController()
let nav = UINavigationController(rootViewController: viewController)
self.navigationController?.present(nav, animated: true, completion: nil)

Android Threads and updates on Main Thread

While working on the android app, I discovered the following error:
Skipped 55 frames!  The application may be doing too much work on its main thread.
I realized I was running heavy processing and UI updates on the same thread. A time consuming task (such as fetching data, filtering arrays) should run in its own thread and when the result is received/achieved the app should run UI update in the main thread.
For instance, in iOS we do:

DispatchQueue.main.async {
	self.tableView.reloadData()
}
Once the data has been received from backend then we run self.tableView.reloadData() in the main thread to present this new data in the view.
Likewise in Android we should run heaving processing tasks in separate threads. We first define the update that we want to happen when we have received the result from a task. We create an instance of the Runnable class which will execute the UI update, in this case show the checkMark icon:

final Runnable checkMarkIsVisible = new Runnable(){
	@Override
	public void run() { 
		checkMark.setVisibility(View.VISIBLE);
	} 
};
Then we create a separate thread for performing the task that can decide whether or not the checkmark will be displayed. Once the result is achieved, we run call the Runnable checkMarkIsVisible on the main thread.
final Handler mainHandler = new Handler(mContext.getApplicationContext().getMainLooper());

new Thread(new Runnable() {
	@Override
	public void run(){
		 //Perform som task
		 if( isItemInList(myItem, myList) ){
		      mainHandler.post(checkMarkIsVisible);
		   }
	}
}).start();

You will not receive the error message anymore.

Edited:

A friend tipped me off after reading this post that instead of having to grab the main thread, you can also run on main thread using runOnUiThread:

new Thread(new Runnable() {
	@Override
	public void run() {
		final String result = performBlockingTask();

		runOnUiThread(new Runnable() {
			@Override
			public void run() {
				mTextView.setText(result);
			}
		});
	}
});