我想知道是否有可能在iPhone应用程序中收到关于自动对焦的通知?
例如,是否存在一种方式可以在自动对焦开始、结束、成功或失败时得到通知?
如果有的话,这个通知的名称是什么?
我想知道是否有可能在iPhone应用程序中收到关于自动对焦的通知?
例如,是否存在一种方式可以在自动对焦开始、结束、成功或失败时得到通知?
如果有的话,这个通知的名称是什么?
我找到了解决方案,以便在自动对焦开始/结束时找到。这很简单,只需使用KVO(键值观察)即可。
在我的UIViewController中:
// callback
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if( [keyPath isEqualToString:@"adjustingFocus"] ){
BOOL adjustingFocus = [ [change objectForKey:NSKeyValueChangeNewKey] isEqualToNumber:[NSNumber numberWithInt:1] ];
NSLog(@"Is adjusting focus? %@", adjustingFocus ? @"YES" : @"NO" );
NSLog(@"Change dictionary: %@", change);
}
}
// register observer
- (void)viewWillAppear:(BOOL)animated{
AVCaptureDevice *camDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
int flags = NSKeyValueObservingOptionNew;
[camDevice addObserver:self forKeyPath:@"adjustingFocus" options:flags context:nil];
(...)
}
// unregister observer
- (void)viewWillDisappear:(BOOL)animated{
AVCaptureDevice *camDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
[camDevice removeObserver:self forKeyPath:@"adjustingFocus"];
(...)
}
文档:
Swift 3
在你的AVCaptureDevice
实例上设置聚焦模式:
do {
try videoCaptureDevice.lockForConfiguration()
videoCaptureDevice.focusMode = .continuousAutoFocus
videoCaptureDevice.unlockForConfiguration()
} catch {}
添加观察者:
videoCaptureDevice.addObserver(self, forKeyPath: "adjustingFocus", options: [.new], context: nil)
重写 observeValue
方法:
override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
guard let key = keyPath, let changes = change else {
return
}
if key == "adjustingFocus" {
let newValue = changes[.newKey]
print("adjustingFocus \(newValue)")
}
}
您可以使用现代的Swift键值观察API,通过观察AVCaptureDeviceInput.device.isAdjustingFocus
属性,在聚焦开始和结束时获取回调。在下面的示例中,AVCaptureDeviceInput
的实例被称为captureDeviceInput
。
示例:
self.focusObservation = observe(\.captureDeviceInput.device.isAdjustingFocus, options: .new) { _, change in
guard let isAdjustingFocus = change.newValue else { return }
print("isAdjustingFocus = \(isAdjustingFocus)")
}
在Swift中,您可以像这样做:
self.observation = videoDeviceInput.device.observe(\.isAdjustingFocus, options: [.old, .new]) { (object, change) in
print("isAdjustingFocus, old = \(change.oldValue), new = \(change.newValue)")
}