I need to perform a live screen capture of the entire iPhone screen. The screen has three container views embedded. One of these containers is a UIImagePickerController. Everything on the screen captures beautifully, but the one container that has the UIImagePickerController is black. I need the whole screen capture so the continuity of operation looks seamless. Is there a way to capture what is currently shown on the screen from a UIImagePickerController? Below is the code I am using to capture the screen image.
I have also tried Apple's Technical Q&A QA1703 .
UIGraphicsBeginImageContextWithOptions(myView.bounds.size, YES, 0.0f);
[myView.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
Thanks in advance for any help!
I've had a similar problem before when trying to capture a screenshot containing both a GLKView and a UIImagePickerController. Sometimes I would get a black screen, other times I would get complaints about an invalid context (when using code similar to yours). I couldn't find a solution, so instead I implemented an AVFoundation camera and haven't looked back since. Here's some quick source code to help you out.
ViewController.h
// Frameworks
#import <CoreVideo/CoreVideo.h>
#import <CoreMedia/CoreMedia.h>
#import <AVFoundation/AVFoundation.h>
#import <UIKit/UIKit.h>
@interface CameraViewController : UIViewController <AVCaptureVideoDataOutputSampleBufferDelegate>
// Camera
@property (strong, nonatomic) AVCaptureSession* captureSession;
@property (strong, nonatomic) AVCaptureVideoPreviewLayer* previewLayer;
@property (strong, nonatomic) UIImage* cameraImage;
@end
ViewController.m
#import "CameraViewController.h"
@implementation CameraViewController
- (void)viewDidLoad
{
[super viewDidLoad];
[self setupCamera];
}
- (void)setupCamera
{
AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo] error:nil];
AVCaptureVideoDataOutput* output = [[AVCaptureVideoDataOutput alloc] init];
output.alwaysDiscardsLateVideoFrames = YES;
dispatch_queue_t queue;
queue = dispatch_queue_create("cameraQueue", NULL);
[output setSampleBufferDelegate:self queue:queue];
NSString* key = (NSString *) kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
[output setVideoSettings:videoSettings];
self.captureSession = [[AVCaptureSession alloc] init];
[self.captureSession addInput:input];
[self.captureSession addOutput:output];
[self.captureSession setSessionPreset:AVCaptureSessionPresetPhoto];
self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
self.previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
// CHECK FOR YOUR APP
self.previewLayer.frame = CGRectMake(0, 0, self.view.frame.size.height, self.view.frame.size.width);
self.previewLayer.orientation = AVCaptureVideoOrientationLandscapeRight;
// CHECK FOR YOUR APP
[self.view.layer insertSublayer:self.previewLayer atIndex:0];
[self.captureSession startRunning];
}
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer,0);
uint8_t *baseAddress = (uint8_t *)CVPixelBufferGetBaseAddress(imageBuffer);
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t width = CVPixelBufferGetWidth(imageBuffer);
size_t height = CVPixelBufferGetHeight(imageBuffer);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef newContext = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst);
CGImageRef newImage = CGBitmapContextCreateImage(newContext);
CGContextRelease(newContext);
CGColorSpaceRelease(colorSpace);
self.cameraImage = [UIImage imageWithCGImage:newImage];
CGImageRelease(newImage);
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
}
// Call whenever you need a snapshot
- (UIImage *)snapshot
{
NSLog(@"SNAPSHOT");
return self.cameraImage;
}
@end
This code captures the input image according to the selected preset (in this case, photo: 852x640), so if you want to capture it along with the view I would recommend the following options:
previewLayer
, which updates its image in the captureOutput
delegate. Pros: WYSIWYG. Cons: May cause your camera to run slower. In both cases above you would need to merge the resulting capture with your other images after taking a screenshot (not as hard as it sounds).
AVFoundation and its associated frameworks are quite daunting, so this is a very lean implementation to get what you're after. If you want more details please check the following examples:
Hope that helps!
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