@property (nonatomic, kopiera, skrivskyddad) NSString * titel, * artist, * genre, * coverUrl, * år; – (Id) initWithTitle: (NSString *) titel artist: (NSString *) artist. NFC Tools is an app which allows you to read, write and program tasks on your NFC tags and other RFID compatible chips. All you need to do is get your device . Re-use/recycle write protected NFC Tags such as hotel key-cards, access badges, price tags, lift cards, key fobs etc You can use this app to associate multiple.
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Don’t despair, you’ll learn how to do this using the Observer pattern: The Command design pattern encapsulates a request or action as an object. The arguments must be passed by pointer. The write function allows you to add as much data as you wish. This creates a toolbar which will display the buttons for the new actions, as well as an array to act as the command queue.
Additionally, wouldn’t it be nice to have an undo option if you delete an album by mistake? When the download is complete, display the image in the image view and use the PersistencyManager to save it locally.
Copy-on-write – Wikipedia
Feel free to read up on these to expand your design pattern horizons. The solution is to forward declare the protocol so that the compiler and Xcode knows that such a protocol will be available. Here’s the source code ,opiera the finished project: You can read more about Target-Action in Apple’s documentation but Invocation uses the NSInvocation class which contains a target object, a method selector and some parameters.
Add the following code to the beginning of viewDidLoad: And that’s where the Observer pattern comes in. It’s good practice to conform to the NSObject protocol — or to conform to a protocol that itself conforms to the Skrivslyddad protocol. Eller ta en global konfiguration hanterare klass: How would you save the Album data to a file? It would probably be a good idea to save the downloaded covers locally so the app won’t need to download the same covers over and over again.
Conversely, you call initWithCoder: The last piece of the HorizontalScroller puzzle is to make sure the album you’re viewing is always centered inside the scroll view.
[sv-users] Calc – tabell / tabellmall
The downloaded images will be saved in the Documents directory, and getImage: So you disable the Undo button. This way, when an image is loaded, the spinner will stop spinning. Build and run your app and check out the beautiful covers inside your HorizontalScroller: If it is, that means there are no more actions to undo. You also need to unregister as an observer when you’re done. Finally, this piece of code sets the scroll view to center the initial view defined by the delegate. However, there are a few things to consider first:.
This provides a great opportunity to talk about the last pattern on the list: The publisher never needs to know anything about the subscribers.
Now, add this code: As mentioned above, the KVO mechanism allows an object to observe changes to a property. Get the album to delete.
If a class keeps a strong pointer to its delegate and the delegate keeps a strong pointer back to the conforming class, your app will leak memory since neither class will release the memory allocated to the other. Enkla och intuitiva, NFC verktyg kan spela standardinformation om dina taggar som kommer att vara kompatibel med alla NFC-enhet.
Add the following code to HorizontalScroller. NFC Tools wakdev Verktyg. You’ll add three method to ViewController.
Skrivksyddad can result in application crashes. It’s simple, yet powerful. In this example the kopira sent is delete’s opposite since when you undo a deletion, you need to add back the deleted album. You execute reload when your data skrivskyddaad changed. The point isn’t to use a design pattern for every line of code you write. You could send out a notification every time an image has been downloaded, but instead, you’ll do that using the other Observer pattern, KVO.
To do this, you’ll need to perform some calculations when the user drags the scroll view with their finger. In both cases we should call the new method to center the current view since the current view probably has changed after the user dragged the scroll view.
When you archive an object which contains other objects, the archiver skrivskyddda tries to recursively archive the child objects and any child objects of the children and so on. Now you can implement the delegate methods; you’ll be amazed at how just a few lines of code can implement a lot of functionality.
Cocoa implements the observer pattern in two familiar ways: Archiving One of Apple’s specialized implementations of the Memento pattern is Archiving.
Indice About Advertise Archives Contact. Always remember to remove your observers when they’re deallocated, skeivskyddad else your app will crash when the subject tries to send messages to these non-existent observers! The undo button is disabled here because the undo stack starts off empty.