ios - 自定义委托(delegate)不更新 iOS 中的 UI

Question

我编写了一个自定义委托(delegate)来监听麦克风音频数据的变化及其长度。当委托(delegate)方法中的数据发生变化时，主 Controller 绘制音频波。结果是主 Controller 中的麦克风数据和长度确实发生了变化，但绘图不显示。

.h 中的委托(delegate)声明:

@class SXDetectAlgorithm;

@protocol SXDetectAlgorithmDelegate <NSObject>

- (void)detectAlgorihtm:(SXDetectAlgorithm *)detectAlgorihtm outputBufferValue:(float *)micBuffer withBufferSize:(UInt32)bufferSize;

@end

@interface SXDetectAlgorithm : NSObject <EZMicrophoneDelegate>

@property (nonatomic, weak) id<SXDetectAlgorithmDelegate> delegate;

@end

在 .m 中实现委托(delegate):

// Use third party API to get microphone data
-(void)    microphone:(EZMicrophone *)microphone
     hasAudioReceived:(float **)buffer
       withBufferSize:(UInt32)bufferSize
 withNumberOfChannels:(UInt32)numberOfChannels {

 // Process the microphone data and then feed to "micBuffer"
 ...
 ...
 ...

 // Back to the main thread to respond delegate
 dispatch_async(dispatch_get_main_queue(), ^{

    SXMainController *mainController = [[SXMainController alloc] init];
    self.delegate = mainController;
    [self.delegate detectAlgorihtm:self outputBufferValue:micBuffer withBufferSize:bufferSize];
});

在 mainController.h 中声明委托(delegate):

@interface SXMainController () <SXDetectAlgorithmDelegate> 

@property (nonatomic, strong) SXDetectAlgorithm *detectAlgorithm;

@end

使用 Delegate 在 mainController.m 中绘制波形:

-(id)initWithCoder:(NSCoder *)aDecoder{

    if(self = [super initWithCoder:aDecoder]) {
        self.detectAlgorithm = [[SXDetectAlgorithm alloc] init];
    }
    return self;
}

- (void)detectAlgorihtm:(SXDetectAlgorithm *)detectAlgorihtm
      outputBufferValue:(float *)lpfout
         withBufferSize:(UInt32)bufferSize {

    dispatch_async(dispatch_get_main_queue(), ^{

    // Plot method...
    // Use a button to test if it can display
    UIButton *testButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 20, 20)];
    testButton.backgroundColor = [UIColor redColor];
    [self.view addSubview:testButton];
    });  
}

我的问题是，即使我返回主线程来绘制波形或显示按钮，mianController 的 UI 也根本不会更新。想了半天问题出在哪里。有人可以给我建议吗？

谢谢。

Answer 1

SXMainController *mainController = [[SXMainController alloc] init];
self.delegate = mainController;
[self.delegate detectAlgorihtm:self outputBufferValue:micBuffer withBufferSize:bufferSize];

每次您收到音频数据时，此代码都会创建一个新的 viewController，这很可能不是您想要实现的。

您可能想要做的是在创建检测对象后将您的 viewController 设置为委托(delegate)，因此:

-(id)initWithCoder:(NSCoder *)aDecoder{

if(self = [super initWithCoder:aDecoder]) {
    self.detectAlgorithm = [[SXDetectAlgorithm alloc] init];
    self.detectAlgorithm = self;
}
return self;
}

然后打电话

self.delegate detectAlgorihtm:self outputBufferValue:micBuffer withBufferSize:bufferSize];

从另一个对象