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On the iPhone you generally want your application to start looking like it did when it was last run to give the user the impression your app is ready to pick up where it left off. NSUserDefaults provides an easy way to store your application’s settings between runs. Simply create an instance of NSUserDefaults and give it the key/value pairs you want it to save.

Storing an integer

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
[prefs setInteger: myIntValue forKey: @"intValueKey"];
[prefs synchronize]; // writes modifications to disk

Reading it back in

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];
int myIntValue = [prefs integerForKey: @"intValueKey"];

or more simply

int myIntValue = [[NSUserDefaults standardUserDefaults] integerForKey: … Continue Reading

I just learned about NSNotificationCenter. Any class in a program can send a notification message to the notification center, and all classes can listen to the center and respond to messages that apply to it. It’s kind of like a callback, but really not.

This is part of my code for implementing a custom keyboard in my iPhone app.

To send a notification named “keyboardDone” to all objects in your program.
[[NSNotificationCenter defaultCenter] postNotificationName: @”keyboardDone” object: nil];

To listen for the “keyboardDone” notification and call the “keyboardDoneObserver:” method when it’s received this can be added to your class’ init code.
[[NSNotificationCenter defaultCenter] addObserver: self … Continue Reading

Xcode’s re-indent command is pretty weak compared to the code reformatting built into other IDEs. It fixes the indentation at the beginning on each line, which makes a huge difference in code readability, but I don’t think it does anything else. In Eclipse and VS I’ve gotten used to being fairly lazy about being consistent with my spacing elsewhere and relying on their built in reformatting to clean it up for me. I wanted to change the way Xcode reformats code, since it’s easier to change tools than to break bad habits.

I spent some time searching for command line code … Continue Reading