iOS Development UI Chapter 16 program start principle and UIApplication

Original http://blog.csdn.net/u010927311/article/details/40145035

IOS Development UI Chapter - program start principle and uiapplication

First, uiapplication

1. Brief introduction

(1) The UIApplication object is a symbol of the application, and a UIApplication object represents an application.

(2) Each application has its own UIApplication object, and is a singleton, if you try to create a new UIApplication object in the program, then the error prompt.

(3) This singleton object can be obtained by [Uiapplicationsharedapplication]

(4) An IOS program is created after the first object is the UIApplication object, and only one (through the code to get two UIApplication objects, the print address can see the address is the same).

(5) Use the UIApplication object to perform some application-level operations

2. Application-level operation examples:

1) Set the application icon in the upper right corner of the red reminder number (such as QQ message, the icon will show 1, 2, 3 new information, etc.). ）

@property (nonatomic) Nsinteger applicationiconbadgenumber;

Code implementation and Effects:

-( ibaction ) changeappnum {

Error, there can be only one unique UIApplication object that can no longer be created

Uiapplication*app=[[uiapplication Alloc]init];

uiapplication *app = [ uiapplication sharedapplication ];

0 to clear the upper right corner of the icon

App. applicationiconbadgenumber = ;

}

2) Set the visibility of the networking indicator

@property (nonatomic,getter=isnetworkactivityindicatorvisible) BOOL networkactivityindicatorvisible;

Code and Effects:

Set up an indicator's networked animation

App. networkactivityindicatorvisible = YES ;

3) Manage status bar

Starting with IOS7, the system provides 2 ways to manage the status bar

A. Through Uiviewcontroller management (each uiviewcontroller can have its own different status bar).

In IOS7, by default, the status bar is managed by Uiviewcontroller, and Uiviewcontroller can easily manage the visibility and style of the status bar by implementing the following methods

The style of the status bar-(Uistatusbarstyle) Preferredstatusbarstyle;

Visibility of the status bar-(BOOL) Prefersstatusbarhidden;

#pragma mark-to set the style of the status bar

-(Uistatusbarstyle) Preferredstatusbarstyle

{

Set to White

return uistatusbarstylelightcontent;

Default is Black

return Uistatusbarstyledefault;

}

#pragma mark-set whether the status bar is hidden (no)

-( BOOL ) Prefersstatusbarhidden

{

return NO ;

}

}

B. Through UIApplication management (the status bar of an application is managed by it uniformly)

If you want to use uiapplication to manage the status bar, you first need to modify the Info.plist settings

Code:

uiapplication *app=[uiapplication sharedapplication];

App. applicationiconbadgenumber = 123 ;

Set up an indicator's networked animation

App. networkactivityindicatorvisible = YES ;

Set the style of the status bar

app.statusbarstyle=uistatusbarstyledefault;//Default (Black)

Set to white + animated effect

[App Setstatusbarstyle : uistatusbarstylelightcontent animated : YES ];

Set whether the status bar is hidden

App. Statusbarhidden = YES ;

Sets whether the status bar hides + animated effects

[App Setstatusbarhidden : YES withanimation : uistatusbaranimationfade ];

C. Supplementary

Since both can be managed on the status bar, when should you use it?

If the style of the status bar is set only once, use uiapplication to manage it.

If the status bar is hidden and the style is different, then use the controller to manage it.

UIApplication to manage has additional benefits that can provide animation effects.

4) OpenURL: Method

UIApplication has a very powerful OpenURL: method

-(BOOL) OpenURL: (nsurl*) URL;

OpenURL: Some of the functions of the method are

Call UIApplication *app =[uiapplicationsharedapplication]; [appopenurl:[nsurlurlwithstring:@ "tel://10086"];

Send SMS [app openurl:[nsurlurlwithstring:@ "sms://10086"];

e-Mail [appopenurl:[nsurlurlwithstring:@ "Mailto://[email protected]"];

Open a webpage resource [appopenurl:[nsurlurlwithstring:@ "http://ios.itcast.cn"];

Open another app OpenURL method to open other apps.

URL Additions:

URL: A Uniform Resource locator that is used to uniquely represent a resource.

URL format: protocol header://Host address/resource path

Network resources: HTTP/FTP, such as Baidu on a picture of the address http://www.baidu.com/images/20140603/abc.png

Local resources: File:///users/apple/desktop/abc.png (host address omitted)

Second, uiapplication Delegate

1. Brief description

All mobile operating systems have a fatal disadvantage: apps are vulnerable to interruptions. For example, a call or lock screen will cause the app to go backstage or even be terminated.

There are a number of other similar situations that can cause the app to be disturbed, causing some system events when the app is disturbed, and UIApplication notifies its delegate object, allowing delegate agents to handle these system events.

Function: When interrupted, notifies the agent to enter the background.

After each new project, there is a class with the word "appdelegate", it is the uiapplication agent, njappdelegate Default has complied with the Uiapplicationdelegate protocol, has been UIApplication's agent.

2. Proxy methods

/**

* When the app is finished, it will be called

*/

-( BOOL ) Application: ( uiapplication *) application didfinishlaunchingwithoptions: ( nsdictionary *) launchoptions

{

NSLog ( @ "%@" , self. window );

NSLog ( @ "didfinishlaunchingwithoptions" );

Override point for Customizationafter application launch.

return YES ;

}

-( void ) Applicationwillresignactive: ( uiapplication *) application

{

}

/**

* Called when the app enters the background

*

* Generally save the app's data (game data, such as pause game)

*/

-( void ) Applicationdidenterbackground: ( uiapplication *) application

{

NSLog ( @ "Applicationdidenterbackground" );

}

-( void ) Applicationwillenterforeground: ( uiapplication *) application

{

NSLog ( @ "Applicationwillenterforeground" );

.

}

-( void ) Applicationdidbecomeactive: ( uiapplication *) application

{

}

/**

* Clear memory that you do not need to use again

*/

-( void ) Applicationdidreceivememorywarning: ( uiapplication *) application

{

NSLog ( @ "applicationdidreceivememorywarning" );

}

-( void ) Applicationwillterminate: ( uiapplication *) application

{

}

@end

Applications typically have five statuses: Official document App.states

Three, the principle of program start

Uiapplicationmain

A uiapplicationmain function is executed in the main function.

Intuiapplicationmain (int argc, char *argv[], nsstring *principalclassname, NSString *delegateclassname);

ARGC, argv: direct transfer to Uiapplicationmain for related processing can be

Principalclassname: Specifies the application class name (symbol of the app), which must be uiapplication (or subclass). If nil, use the UIApplication class as the default value

Delegateclassname: Specifies the application's proxy class, which must comply with the Uiapplicationdelegate protocol

The Uiapplicationmain function creates a UIApplication object based on Principalclassname, creates a delegate object from Delegateclassname, and assigns the delegate object to the UI The delegate property in the Application object

The application's Main Runloop (the event loop) is then created, and the event is processed (the application:didfinishlaunchingwithoptions of the delegate object is called first after the program is completed: method)

The Uiapplicationmain function returns when the program exits normally

#import <UIKit/UIKit.h>

#import "TXAppDelegate.h"

int Main ( int argc, Char * argv[])

{

@autoreleasepool {

Return Uiapplicationmain (argc, Argv,nil, Nsstringfromclass ([Txappdelegate class]));

@autoreleasepool {

Returnuiapplicationmain (argc, argv, nil, @ "mjappdelegate");

Returnuiapplicationmain (argc, argv, @ "uiapplication", @ "Mjappdelegate");

Return Uiapplicationmain (argc, Argv,nil, Nsstringfromclass ([Yyappdelegate class]));

Return Uiapplicationmain (argc, argv,@ "UIApplication", Nsstringfromclass ([Yyappdelegate class]);

/*

ARGC: Number of parameters passed in by the system or user

ARGV: Actual parameters passed in by the system or user

1. Create a UIApplication object based on the third parameter passed in

2. Based on the fourth incoming agent that created the UIApplication object

3. Set the proxy object that you just created for uiapplication

4. Turn on an event loop

*/

return Uiapplicationmain (argc, argv, nsstringfromclass ([ uiapplication class ]), nsstringfromclass ([ Txappdelegate class ]));

}

}

Code and parameter description for system entry:

ARGC: System or user-passed parameters

ARGV: Actual parameters passed in by the system or user

1. Create a UIApplication object based on the third parameter passed in

2. Based on the fourth incoming agent that created the UIApplication object

3. Set the proxy object that you just created for uiapplication

4. Turn on an event loop (which can be understood as a dead loop inside) This time loop is a queue (FIFO) first added first processing

iOS Program Start principle

Iv. complete process of program initiation

1.main function

2.UIApplicationMain

* Create UIApplication objects

* Create a UIApplication delegate object

3.delegate object starts processing (listening) system events (no storyboard)

* When the program is started, the agent's application:didfinishlaunchingwithoptions is called: method

* Create UIWindow in application:didfinishlaunchingwithoptions:

* Create and set UIWindow Rootviewcontroller

* Display window

3. According to Info.plist to obtain the most important storyboard file name, load the main storyboard (with storyboard)

* Create UIWindow

* Create and set UIWindow Rootviewcontroller

* Display window

iOS Development UI Chapter 16 program start principle and UIApplication