The first IOS program in IOS

I have been doing J2EE development before, but I have not been familiar with objective-C for the first time. I think it is very strange about its syntax. After a week of study, I finally learned the objective-C syntax and started iOS development, watch the basic OC video of Chuanzhi, write the demo and analyze the principle of the IOS program running, and take the following notes:

1. Each application has its own interface, uiwindow inherited from uiview.
Uiview: view, all visible and tangible on the screen is a uiview
2. Problems with uiview:
(A) switching between uiviews
(B) Manage the lifecycle of a uiview
(C) assemble data sources for uiview
 
The above three points are completed by the Controller (uiviewcontroller ).

Uiviewcontroller: by default, a uiview is provided internally to manage the life cycle,
Assemble data to uiview to display and process uiview events

IOS adopts the MVC design mode.

Operating principle:
1. First, execute the main function.
2. Run the uiapplicationmain function.
3. Inside the uiapplicationmain Function
Uiapplicationmain: The third parameter specifies the application Class Name (or subclass). If it is nil, the default value is uiapplication. The fourth parameter specifies the proxy class name.
1> Create a uiapplication instance. This uiapplication is a singleton. An IOS program corresponds to a uiapplication object.
2> the uiapplication object is a symbol of the application.
3> enable a message loop (main loop): used to listen to events on the mobile phone
4> Create another delegate object for uiapplication to monitor the lifecycle of uiapplication.

5> when the life cycle of the uiapplication changes, different messages are sent to the delegate.
* When you run the program for the first time:
Didfinishlaunchingwitexceptions (loaded)->
Applicationdidbecomeactive (get focus)->
* When you click the Home key:
Applicationwillresignactive (out of focus)->
Applicationdidenterbackground (entering the background)
* When you click the application icon again
Applicationwillenterforeground (entering the foreground)->
Applicationdidbecomeactive (get Focus)

Create an iOS Project
# Import "gpbappdelegate. H"
# Import "gpbviewcontroller. H"
@ Implementation gpbappdelegate

-(Void) dealloc
{
[_ Window release];
[_ Viewcontroller release];
[Super dealloc];
}
# Call after The Pragma mark application is loaded
-(Bool) Application :( uiapplication *) Application didfinishlaunchingwitexceptions :( nsdictionary *) launchoptions
{
Nslog (@ "didfinishlaunchingwithoptions-> Load completed ");
// Initialize a window
Self. Window = [[[uiwindow alloc] initwithframe: [[uiscreen mainscreen] bounds] autorelease];
// Override point for customization after application launch.
// Input the XIB file name to initialize the yige Controller
Self. viewcontroller = [[[gpbviewcontroller alloc] initwithnibname: @ "gpbviewcontroller" Bundle: Nil] autorelease];
// Set the root controller of the window
Self. Window. rootviewcontroller = self. viewcontroller;


// The window is not displayed by default. You need to call the display method.
// Keywindow is the main window. Only the main window can interact with users.
[Self. Window makekeyandvisible];
// Self. Window. Hidden = no;
Return yes;
}

# Call When The Pragma mark program loses focus (no interaction with users)
-(Void) applicationwillresignactive :( uiapplication *) Application
{
Nslog (@ "applicationwillresignactive-> lose focus ");
}
# Pragma Mark called when the application enters the background (click the home key)
-(Void) applicationdidenterbackground :( uiapplication *) Application
{
Nslog (@ "applicationdidenterbackground-> enter the background ");
}
# Pragma Mark called when the application enters the foreground
-(Void) applicationwillenterforeground :( uiapplication *) Application
{
Nslog (@ "applicationwillenterforeground-> enter the foreground ");
}
# Pragma Mark called when the application gets the focus
-(Void) applicationdidbecomeactive :( uiapplication *) Application
{
Nslog (@ "applicationdidbecomeactive-> get focus ");
}
# The Pragma mark program is called when it is terminated in some cases
-(Void) applicationwillterminate :( uiapplication *) Application
{
Nslog (@ "applicationwillterminate-> terminate ");
}

@ End

Gpbviewcontroller. M file:
# Import "gpbviewcontroller. H"

@ Interface gpbviewcontroller ()
@ End

@ Implementation gpbviewcontroller

-(Ibaction) login {
Nsstring * name = _ name. text;
Nsstring * Pwd = _ PWD. text;

Nslog (@ "name = % @, password = % @", name, PWD );
// The view that calls out the keyboard is the first responder (firstresponder)
// Indicates this view. If you don't want to be the first responder, exit the keyboard.
// [_ Name resignfirstresponder];
// [_ PWD resignfirstresponder];

// If the first responder exists in self. view, you can exit the keyboard.
[Self. View endediting: Yes];
}

-(Void) viewdidload
{
[Super viewdidload];
// Do any additional setup after loading the view, typically from a nib.
}
-(Void) didreceivememorywarning
{
[Super didreceivememorywarning];
// Dispose of any resources that can be recreated.
}
@ End