Display portrait and landscape format picture in equal size using a video projector

Do you also feel that this is the big disadvantage of modern picture projection compared to the old-fashioned slides: portrait format is really handicaped because you have two big black bars on the left and right hand sides. Video projectors have an aspect ratio of 4:3 or even 16:9 compared to the squared display size of old slide projectors. Weiterlesen

Performance of Swift vs. Objective-C and the Debugger

Recently I have migrated an old project of mine from Objective-C to Swift. It was not that difficult and it worked out fine, and I was eager to see how the performance of the migrated system would turn out. How big was my disappointment when I saw that the Swift version of my system was at least a factor of 10 slower than the Objective-C version with unchanged functionality. That can’t be true, I thought and debugged at little bit.


Trusted Domains in NextCloud

Recently I installed NextCloud as a common storage for our choir on some hosted server. Everything worked fine beside the usual little problems during installation procedures. Also my fellow choir members were quite happy with new system but a few of them were complaining that they could not login to the NextCloud. The error message they got was something like „Access through untrusted domain“. Well, I could not imagine what happened here. The SSL certificate was correctly installed and valid. And why did it happen only to a few of them and not all? Weiterlesen

UIDocumentBrowserViewController and External Storage

Some time ago I’ve ported the old and ancient strategy game „Empire“ from macOS to iOS. On macOS I decided to make the game document based. Since the game may last many hours (or even more), it is necessary to store the state of the game in some kind of document to continue it in a later session. On start-up of the game it tries to re-open the last used document. That’s quite easy with the recentDocumentURLs array of the NSDocumentController.

But for iOS such a facility is missing. There is no such thing as a „UIDocumentController“ and the UIDocumentBrowserViewController tells you nothing about recently opened or created documents. I wanted to make the iOS version of Empire document based as well to enable anytime switches between the iOS and macOS version of the game. That’s especially interesting, if the game document is stored on some external server (like iCloud).


LinkedList: NSCoding protocol

In my previous post I’ve explained that the new Codable protocol of Swift 4 has some problems with references to objects (i.e. class instances). Or, better said, the two implementations of coders available

  • ProperListEncoder/PropertyListDecoder
  • JSONEncoder/JSONDecoder

have this problem: they expand all references to new objects and create doublets if references in the object tree occur more than once for a single object. In the case of loops in the object tree (references of objects to each other) the encoding leads to an endless loop.

The old NSKeyedArchiver/NSKeyedUnarchiver of the Objective C-world do not have this problem: they respect references and restore them correctly at unarchiving. So, I want to implement this old way, i.e. the NSCoding protocol in my LinkedList as well. Remark: LinkedList uses references to its payload as well even in loops but that is taking care of even in the use of the Coding protocol.