Yes, you still need to actually create the scroller and add it to your main view but before doing that, add the following method:. After the undoAction has been created you add it to the undoStack. The scroll view completely fills the HorizontalScroller. The undo button is disabled here because the undo stack starts off empty.
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This converts an object into a stream that can be saved and later restored without exposing private properties to external classes. Copy-on-write — Wikipedia This object can be changed dynamically and executed when needed. Add the following code to the class extension in ViewController. You can read more about this functionality in Chapter 16 of the iOS 6 skrivskydsad Tutorials book.
Now add the following code to reload the scroller: In both cases we should koliera the new method to center the current view since the current view probably has changed after the user dragged the scroll view.
The Command design pattern encapsulates a request or action as an object. Observer, Memento, ansvarskedjan och Command. The publisher never needs to know anything about the subscribers. For example, a simple motion with your phone in front of your NFC tag before going to sleep and the WiFi will turn off, the phone will switch to silence and your alarm will be set for the next morning, all by itself.
When this class is deallocated, it removes itself as an observer from all notifications it had registered for. Since the main application accesses all services via LibraryAPIthis is how the application will let PersitencyManager know that it needs to save album data.
Du har lagt till Album klassen men du har inte underklassas det. Finally, add the method for the undo action: Now, add this code: Scroll to an album as before, stop the app, then relaunch to make koiera the skrifskyddad is fixed:. The write function allows you to add as much data as you wish. I init du fylla arrayen med fem prov album. The id means that the delegate can only be assigned classes that conform to HorizontalScrollerDelegategiving you some type safety.
Required skrisvkyddad must be implemented by the delegate and usually contain some data that is absolutely required by the class. Later on, this externalized state can be restored without violating encapsulation; that skrivskyddas, private data remains private. Get the album to delete. That loads the previously saved state when the app starts.
The Command Pattern The Command design pattern encapsulates a request or action as an object. This method loads album data via LibraryAPI and then sets the currently displayed view based on the current value of the current view index. As mentioned above, the KVO mechanism allows an object to observe changes to a property. You execute reload when your data has changed. The scroll view completely fills the HorizontalScroller.
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