iPhone Countdown App

Open up Xcode and click: File->New Project.

Select: iPhone OS ->Applications-> View-Based Application and name it whatever you would like.

Lets start with the UIView.

Double Click .xib” to launch “Interface Builder”

Click: Tools -> Reveal In Document Window -> View
Click: Tools -> Attributes Inspector
Select the background attribute and set it to Black
Now add a UILabel, it should be as simple as dragging it out of from Tools->Library.

To reference this label in our code we need to change its outlet id.

In the document window “File’s Owner”
Click: Tools->Idenity Inspector
In the inspector click the + under “Class Outlets”
Change myOutlet1 to “countdownLabel”
Change id to UILabel
Click enter to make sure they commit
Now lets generate the code for the controller we just created.

Still in interface builder make sure “File’s Owner” is still selected in the Document Explorer
Click: File->Write Class Files
Make sure you select your active target, which should be the name of your program.
Now we need to wire up the Label in Interface Builder to the UILabel in the class file

Reopen Interface Builder
Select the Label in the View or in Document Window
Click: Tools -> Connection Inspector
Move your mouse cursor over the empty circle to the right of text “New Referencing Outlet” (the circle will change to a Plus(+))
Mouse Click then drag the Plus (+) to “File’s Owner” in Document Window
When you release select countdownLabel in the popup list
Click: File -> Save then close Interface Builder
Creating the timer

In xCode open
In Controller.h add the line -(void)updateLabel; right before the line @end
In Controller.c add the lines
-(void)updateLabel {
}
right before the line @end

In Delegate.h add the field “NSTimer *timer;” and the method signature “-(void) onTimer;”
In Delegate.m
Start the timer in “applicationDidFinishLaunching”
Add the method onTimer that will update the label in the view controller
Invalidate the timer in the method “applicationWillTerminate”
release the timer in dealloc
Updating the label

Open Controller.c
Add a font in method “viewDidLoad”
Add code to get current time and update label in our new “updateLabel” method.
Build & Go!