我对目标C语言世界还很陌生，但是这个问题似乎比快速的Google搜索复杂得多。我正在使用Ionic / Cordova，并且创建了自己的插件，并且该插件已经在Android上100％运行了一段时间。我的任务是开发可在iOS上使用的插件。
该插件包含Cordova Camera Preview插件的修改版和Firebase MLKit入门演示。我正在利用它来使Camera Preview在后台运行，以便使用Firebase MLKit TextRecognizer进行实时文本识别。
我当前的问题似乎是AVCaptureSession，因为该应用程序甚至在Capture Session运行之前一直崩溃。尝试运行相机会话时，我会收到“由于内存问题导致应用程序终止”。
我已经在Google和Stackoverflow上尝试了多种修复程序，但是似乎没有一种对我有用。我当前用于调试的设备是运行iOS 12.3.1的iPhone 7 Plus。
在主代码文件下面启动AVCaptureSession并读取输出：
.H文件：
#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>
NS_ASSUME_NONNULL_BEGIN
@interface CameraViewController : UIViewController
- (void)setDeviceSize:(CGFloat)width height:(CGFloat)height x:(CGFloat)x y:(CGFloat)y;
- (void)startCameraSession:(void(^)(BOOL started))completion;
- (void)startCameraCaptureSession;
@end
NS_ASSUME_NONNULL_END
.M文件：
#import "CameraViewController.h"
#import "UIUtilities.h"
@import AVFoundation;
@import CoreVideo;
@import FirebaseMLVision;
@import FirebaseMLCommon;
NS_ASSUME_NONNULL_BEGIN
static NSString *const videoDataOutputQueueLabel = @"com.google.firebaseml.visiondetector.VideoDataOutputQueue";
static NSString *const sessionQueueLabel = @"com.google.firebaseml.visiondetector.SessionQueue";
static NSString *const noResultsMessage = @"No Results";
static const CGFloat FIRconstantScale = 1.0;
static BOOL isBusyProcessing = false;
static BOOL shouldScanAndProcess = false;
static BOOL isCameraOutputFinish = false;
static BOOL isCameraInputFinish = false;
static BOOL isCameraSetupFinish = false;
static CGFloat deviceX = (CGFloat)0;
static CGFloat deviceY = (CGFloat)0;
static CGFloat deviceHeight = (CGFloat)0;
static CGFloat deviceWidth = (CGFloat)0;
static int startupActionsCompleted = 0;
static dispatch_queue_t backgroundQueue;
@interface CameraViewController () <AVCaptureVideoDataOutputSampleBufferDelegate>
@property (nonatomic, nonnull) AVCaptureVideoPreviewLayer *previewLayer;
@property (nonatomic) AVCaptureSession *captureSession;
@property (nonatomic) dispatch_queue_t sessionQueue;
@property (nonatomic) FIRVision *vision;
@property (nonatomic) UIImageView *previewOverlayView;
@property (nonatomic) UIView *cameraView;
@property (nonatomic) CMSampleBufferRef lastFrame;
@end
@implementation CameraViewController
- (CameraViewController*)init{
backgroundQueue = dispatch_queue_create("session queue", DISPATCH_QUEUE_SERIAL);
return self;
}
- (void)setDeviceSize:(CGFloat)width height:(CGFloat)height x:(CGFloat)x y:(CGFloat)y {
deviceWidth = width;
deviceHeight = height;
deviceX = x;
deviceY = y;
}
- (void)startCameraSession:(void(^)(BOOL started))completion{
dispatch_async(dispatch_get_main_queue(), ^{
_cameraView = self.view;
isCameraInputFinish = false;
isCameraOutputFinish = false;
isCameraSetupFinish = false;
_captureSession = [[AVCaptureSession alloc] init];
_sessionQueue = dispatch_queue_create(sessionQueueLabel.UTF8String, nil);
_vision = [FIRVision vision];
_previewOverlayView = [[UIImageView alloc] initWithFrame:CGRectMake(deviceX, deviceY, deviceWidth, deviceHeight)];
startupActionsCompleted = 0;
self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:_captureSession];
[self setUpPreviewOverlayView:completion];
[self setUpCaptureSessionOutput:completion];
[self setUpCaptureSessionInput:completion];
});
}
- (void)startCameraCaptureSession{
[self startSession];
}
- (void)viewDidLoad {
[super viewDidLoad];
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
}
- (void)viewDidDisappear:(BOOL)animated {
[super viewDidDisappear:animated];
[self stopSession];
}
- (void)viewDidLayoutSubviews {
[super viewDidLayoutSubviews];
_previewLayer.frame = _cameraView.frame;
}
#pragma mark - Private
- (void)setUpCaptureSessionOutput:(void(^)(BOOL started))completion {
dispatch_async(_sessionQueue, ^{
[self->_captureSession beginConfiguration];
self->_captureSession.sessionPreset = AVCaptureSessionPresetMedium;
AVCaptureVideoDataOutput *output = [[AVCaptureVideoDataOutput alloc] init];
output.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey: [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA]};
dispatch_queue_t outputQueue = dispatch_queue_create(videoDataOutputQueueLabel.UTF8String, nil);
[output setSampleBufferDelegate:self queue:outputQueue];
if ([self.captureSession canAddOutput:output]) {
[self.captureSession addOutput:output];
[self.captureSession commitConfiguration];
} else {
NSLog(@"%@", @"Failed to add capture session output.");
}
startupActionsCompleted++;
isCameraOutputFinish = true;
if(isCameraInputFinish) {
isCameraSetupFinish = true;
}
if (startupActionsCompleted >= 3) {
dispatch_async(backgroundQueue, ^{
completion(true);
});
}
});
}
- (void)setUpCaptureSessionInput:(void(^)(BOOL started))completion {
dispatch_async(_sessionQueue, ^{
AVCaptureDevicePosition cameraPosition = AVCaptureDevicePositionBack;
AVCaptureDevice *device = [self captureDeviceForPosition:cameraPosition];
if (device) {
[self->_captureSession beginConfiguration];
NSArray<AVCaptureInput *> *currentInputs = self.captureSession.inputs;
for (AVCaptureInput *input in currentInputs) {
[self.captureSession removeInput:input];
}
NSError *error;
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (error) {
NSLog(@"Failed to create capture device input: %@", error.localizedDescription);
return;
} else {
if ([self.captureSession canAddInput:input]) {
[self.captureSession addInput:input];
} else {
NSLog(@"%@", @"Failed to add capture session input.");
}
}
[self.captureSession commitConfiguration];
} else {
NSLog(@"Failed to get capture device for camera position: %ld", cameraPosition);
}
startupActionsCompleted++;
isCameraInputFinish = true;
if (isCameraOutputFinish) {
isCameraSetupFinish = true;
}
if (startupActionsCompleted >= 3) {
dispatch_async(backgroundQueue, ^{
completion(true);
});
}
});
}
- (void)startSession {
dispatch_async(_sessionQueue, ^{
[self->_captureSession startRunning];
});
}
- (void)stopSession {
dispatch_async(_sessionQueue, ^{
[self->_captureSession stopRunning];
});
}
- (void)setUpPreviewOverlayView:(void(^)(BOOL started))completion {
[_cameraView addSubview:_previewOverlayView];
startupActionsCompleted++;
if (startupActionsCompleted >= 3) {
dispatch_async(backgroundQueue, ^{
completion(true);
});
}
}
- (void)recognizeTextOnDeviceInImage:(FIRVisionImage *)image width:
(CGFloat)width height:(CGFloat)height {
FIRVisionTextRecognizer *textRecognizer = [_vision onDeviceTextRecognizer];
dispatch_group_t group = dispatch_group_create();
dispatch_group_enter(group);
[textRecognizer processImage:image completion:^(FIRVisionText * _Nullable text, NSError * _Nullable error) {
isBusyProcessing = false;
if (text == nil) {
NSLog(@"On-Device text recognizer error: %@", error ? error.localizedDescription : noResultsMessage);
dispatch_group_leave(group);
return;
}
for (FIRVisionTextBlock *block in text.blocks) {
NSArray<NSValue *> *points = [self convertedPointsFromPoints:block.cornerPoints width:width height:height];
for (FIRVisionTextLine *line in block.lines) {
NSArray<NSValue *> *points = [self convertedPointsFromPoints:line.cornerPoints width:width height:height];
for (FIRVisionTextElement *element in line.elements) {
CGRect normalizedRect = CGRectMake(element.frame.origin.x / width, element.frame.origin.y / height, element.frame.size.width / width, element.frame.size.height / height);
CGRect convertedRect = [self->_previewLayer rectForMetadataOutputRectOfInterest:normalizedRect];
UILabel *label = [[UILabel alloc] initWithFrame:convertedRect];
label.text = element.text;
label.adjustsFontSizeToFitWidth = YES;
}
}
}
dispatch_group_leave(group);
}];
dispatch_group_wait(group, DISPATCH_TIME_FOREVER);
}
- (AVCaptureDevice *)captureDeviceForPosition:(AVCaptureDevicePosition)position {
if (@available(iOS 10, *)) {
AVCaptureDeviceDiscoverySession *discoverySession =
[AVCaptureDeviceDiscoverySession discoverySessionWithDeviceTypes:@[AVCaptureDeviceTypeBuiltInWideAngleCamera]
mediaType:AVMediaTypeVideo
position:AVCaptureDevicePositionUnspecified];
for (AVCaptureDevice *device in discoverySession.devices) {
if (device.position == position) {
return device;
}
}
}
return nil;
}
- (void)updatePreviewOverlayView {
dispatch_sync(dispatch_get_main_queue(), ^{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(_lastFrame);
if (imageBuffer == nil) {
return;
}
CIImage *ciImage = [CIImage imageWithCVPixelBuffer:imageBuffer];
CIContext *context = [[CIContext alloc] initWithOptions:nil];
CGImageRef cgImage = [context createCGImage:ciImage fromRect:ciImage.extent];
if (cgImage == nil) {
return;
}
UIImage *rotatedImage = [UIImage imageWithCGImage:cgImage scale:FIRconstantScale orientation:UIImageOrientationRight];
_previewOverlayView.image = rotatedImage;
CGImageRelease(cgImage);
});
}
- (NSArray <NSValue *>*)convertedPointsFromPoints:(NSArray<NSValue *> *)points
width:(CGFloat)width
height:(CGFloat)height {
NSMutableArray *result = [NSMutableArray arrayWithCapacity:points.count];
for (NSValue *point in points) {
CGPoint cgPointValue = point.CGPointValue;
CGPoint normalizedPoint = CGPointMake(cgPointValue.x / width, cgPointValue.y / height);
CGPoint cgPoint = [_previewLayer pointForCaptureDevicePointOfInterest:normalizedPoint];
[result addObject: [NSValue valueWithCGPoint:cgPoint]];
}
return result;
}
- (void)captureOutput:(AVCaptureOutput *)output didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection {
if (isCameraSetupFinish) {
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
if (imageBuffer) {
_lastFrame = sampleBuffer;
[self updatePreviewOverlayView];
if (!isBusyProcessing && shouldScanAndProcess) {
isBusyProcessing = true;
FIRVisionImage *visionImage = [[FIRVisionImage alloc] initWithBuffer:sampleBuffer];
FIRVisionImageMetadata *metadata = [[FIRVisionImageMetadata alloc] init];
UIImageOrientation orientation = [UIUtilities imageOrientationFromDevicePosition:AVCaptureDevicePositionBack];
FIRVisionDetectorImageOrientation visionOrientation = [UIUtilities visionImageOrientationFromImageOrientation:orientation];
metadata.orientation = visionOrientation;
visionImage.metadata = metadata;
CGFloat imageWidth = CVPixelBufferGetWidth(imageBuffer);
CGFloat imageHeight = CVPixelBufferGetHeight(imageBuffer);
dispatch_async(_sessionQueue, ^{
[self recognizeTextOnDeviceInImage:visionImage width:imageWidth height:imageHeight];
});
}
} else {
NSLog(@"%@", @"Failed to get image buffer from sample buffer.");
}
// Had To Remove this as it caused bad memory errors...
//CFRelease(sampleBuffer);
//CFRelease(imageBuffer);
}
}
@end
NS_ASSUME_NONNULL_END
呼叫代码：
- (void)startScanner:(CDVInvokedUrlCommand*)command
{
CDVPluginResult *pluginResult;
if (self.cameraViewController != nil) {
pluginResult = [CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsString:@"Scanner Started"];
[self.commandDelegate sendPluginResult:pluginResult callbackId:command.callbackId];
return;
}
CGFloat x = (CGFloat)((Float32)0) + self.webView.frame.origin.x;
CGFloat y = (CGFloat)((Float32)0) + self.webView.frame.origin.y;
CGFloat width = (CGFloat)[command.arguments[1] floatValue];
CGFloat height = (CGFloat)[command.arguments[0] floatValue];
CGRect frameRect = CGRectMake(x, y, width, height);
self.cameraViewController = [[CameraViewController alloc] init];
[self.cameraViewController setDeviceSize:width height:height x:x y:y];
self.cameraViewController.view.frame = frameRect;
[self.viewController addChildViewController:self.cameraViewController];
self.webView.opaque = NO;
self.webView.backgroundColor = [UIColor clearColor];
[self.webView.superview addSubview:self.cameraViewController.view];
[self.webView.superview bringSubviewToFront:self.webView];
// Start Camera and wait for completion
[self.cameraViewController startCameraSession:^(BOOL started){
// Memory issues start before I even call the "startRunning" method
[self.cameraViewController startCameraCaptureSession];
[self.commandDelegate sendPluginResult:[CDVPluginResult resultWithStatus:CDVCommandStatus_OK messageAsString:@"Scanner Started"] callbackId:command.callbackId];
}];
}
我已经注释掉.M文件（setUpPreviewOverlayView，setUpCaptureSessionOutput，setUpCaptureSessionInput）中的几乎所有内容，因此这只能使我指出我错误地调用了AVCaptureSession的方向吗？
任何帮助将不胜感激：）