[Application proxy object ApplicationDelegate-Introduction to the application startup process Objective-C language]

1. Let’s continue what we said yesterday.

1. Some people are a little confused about the last part of yesterday’s content. Let’s review it again.

1) When we first started, did we put a button in Main.storyboard?

2) As for me, I want to perform some operations when I click the button, right?

So, I dragged an event to it,

Drag it into the class implementation,

3) So, first of all, step one: what we demonstrate is getting this application object:

Then, get the application object. For example, if it is a singleton, how to verify that it is a singleton?

Have you obtained it twice and printed their addresses? Are they exactly the same, right?

This is our application, a singleton.

Now don't worry about what a singleton is. When it comes to networks and multi-threading, I will explain how to write this singleton.

3) Set the number on the application avatar,

The default is 0, no number, right?

Then if you want to display numbers, just set it directly,

app.applicationIconBadgeNumber = 10 ；

However, there is one thing to note,

After iOS8.0, do you need to register?

Then, app is your current application.

Notification settings that require registered users:

Then, user permission is required, right?

If the user does not allow you to push, can you push? Is it impossible?

You can’t set the avatar number for your application either.

And, this part of the code:

It is only executed once.

I don’t know if you have noticed when writing code,

Will it prompt you next time you run it?

No way,

Yes, this is a reminder only once.

This is also managed by the system for us.

You don't need to worry,

And that is, after you execute this code for the first time:

Just to remind you,

Sometimes the apps we download, such as WeChat or Alipay,

When you use the camera, you will be reminded to allow this app to open the camera.

Then, you click "Allow" and it can open the camera.

What about this one? It only reminds you once. When you use it, it reminds you again.

And if you come again in the future, this reminder operation will not be performed again.

So, what should you do if the user does not allow you to set it?

Then, if he wants to use this function next time, do you have to remind him to turn on this function in the settings?

Yes, just give me a reminder.

This is the number on the set avatar,

4) There is also a network indicator,

Network status indicator,

Do you know where it is?

The chrysanthemum in the upper left corner, right?

5) Then, there is openURL: just understand this,

6) The last one, status bar management:

How to operate status bar management?

By default, this status bar is managed by the controller.

Then some students may ask, why should we give this status bar to the application, right?

Let me explain to you why we need to hand over this status bar to the application.

Well, in our application, we say, a complete application,

It can't have only one interface, right?

There can't be only one controller, right?

Otherwise, there would be nothing I want to talk about today.

So, there are many controllers, do you have to perform an operation in each one:

Suppose that my application has a relatively deep background.

Now, I want to change the status bar to a light color.

Then do you need to write it once in each controller?

If you don't give it to the application, then in each one, write it once,

Then, you have to hand it over to the application. Is it enough to set it up once?

We are just demonstrating a Hidden now.

In fact, it can also set its Style:

Do you see it:

Can you set it to a light color effect?

Press the command key and enter:

UIStatusBarStyle：

Click to enter:

LightContent：

command + C、

return,

command + V：

Are we in the controller earlier, prefersStatusBarStyle?

No problem, right?

Then, you can do all of this at once through the application:

You don’t need to do it manually anymore, just write each controller one by one.

I won’t demonstrate this anymore, I’ll comment it out:

But, for example, in Xcode7.0, you have to hand over the management of the status bar to the application. How do you do it?

Have we added a Key to the info.plist file?

View Controller-based status bar：NO

Where is this Key?

Click the plus sign. Is it at the bottom?

There’s no need to remember, just scroll to the bottom and that’s it.

Right at the bottom,

Then, turn it off and set it to NO.

Is that enough?

The management of this status bar is left to the application.

You must know this,

Okay, what about these?