ios 从视图控制器获取 appdelegate 值
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Getting appdelegate value from viewcontroller
提问by AlgoCoder
In Appdelegate.h
I imported the playerviewcontrollerin both Appdelegate.hand Appdelegate.mfiles.
在Appdelegate.h
我进口playerviewcontroller均Appdelegate.h和Appdelegate.m文件。
@class PlayerViewController;
@property(nonatomic)float volumeDelegate;
In Appdelegate.m
在 Appdelegate.m
@synthesize volumeDelegate;
- (void)volumeChanged:(NSNotification *)notification
{
volumeDelegate =1.0
PlayerViewController *volumeObject=[[PlayerViewController alloc]init];
[volumeObject setVolumeForAVAudioPlayer];
}
In Playerviewcontroller.h
在 Playerviewcontroller.h 中
-(void)setVolumeForAVAudioPlayer;
In Playerviewcontroller.m
在 Playerviewcontroller.m 中
@interface PlayerViewController ()
{
AppDelegate *appdelegate;
}
-(void)viewDidLoad
{
appdelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
}
-(void)setVolumeForAVAudioPlayer
{
[appdelegate.sharedplayer setVolume:appdelegate.volumeDelegate];
NSLog(@"System Volume in player view: %f",appdelegate.volumeDelegate);
}
When i run this I get volumeDelegatevalue as Zero as below.
当我运行它时，我得到的volumeDelegate值为零，如下所示。
System Volume in player view:0.000000000
播放器视图中的系统音量：0.000000000
What is the Mistake I'm making here
我在这里犯了什么错误
回答by Hemang
You can access to the AppDelegateobject like below
您可以访问AppDelegate如下对象
Objective-C
目标-C
Define it like this:
像这样定义它：
AppDelegate appDelegate;
Access it like this:
像这样访问它：
appDelegate = (AppDelegate *)[UIApplication sharedApplication].delegate;
Usage:
用法：
- (void)setVolumeForAVAudioPlayer
{
[appDelegate.sharedplayer setVolume:appdelegate.volumeDelegate];
NSLog(@"System Volume in player view: %f",appDelegate.volumeDelegate);
}
Swift:
迅速：
Define it like this:
像这样定义它：
let appDelegate = UIApplication.shared.delegate as! AppDelegate
Usage:
用法：
func setVolumeForAVAudioPlayer()
{
appDelegate.sharedPlayer.setVolume:appDelegate.VolumeDelegate
print("System Volume in player view: \(appDelegate.volumeDelegate)")
}
回答by iHunter
You're initializing the appdelegatemember variable in a viewDidLoad, but that method is not called at the moment you call setVolumeForAVAudioPlayer!
您正在 a 中初始化appdelegate成员变量viewDidLoad，但在您调用setVolumeForAVAudioPlayer!
You're doing
你正在做的
PlayerViewController *volumeObject=[[PlayerViewController alloc]init];
[volumeObject setVolumeForAVAudioPlayer];
But alloc initdoesn't make viewController's view to load! viewDidLoadis not called at all.
但alloc init不会使 viewController 的视图加载！viewDidLoad根本没有被调用。
