Weird UIScrollview behaviour in IOS 7 in IPhone 4 - ios

Question

I am working on a video-related application. For this, I used AVFoundation framework to capture image and video. I am capturing an image and showing that captured image in next view, where image view is a subview to the scrollview. It's working fine in iPhone 5,iPhone 5s and also in iPad but in iPhone 4 after capturing the image and while attaching to scrollView, the app is becoming slow. The scroll view is not scrolling smoothly as in other devices. I am not getting issue where it has gone wrong. I am using the below code to capture images:
-(void)capturePhoto
{
_ciContext = [CIContext contextWithOptions:nil];
AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
// - input
AVCaptureDeviceInput *deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:NULL];
NSError *error = nil;
if ([device lockForConfiguration:&error])
{
if ([device isFlashModeSupported:AVCaptureFlashModeOff])
{
device.flashMode = AVCaptureFlashModeOff;
}
[device unlockForConfiguration];
}
// - output
_dataOutput = [[AVCaptureStillImageOutput alloc] init];
NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys:
AVVideoCodecJPEG, AVVideoCodecKey, nil];
_dataOutput.outputSettings = outputSettings;
// - output
NSMutableDictionary *settings;
settings = [NSMutableDictionary dictionary];
[settings setObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
forKey:(__bridge id) kCVPixelBufferPixelFormatTypeKey];
_dataOutputVideo = [[AVCaptureVideoDataOutput alloc] init];
_dataOutputVideo.videoSettings = settings;
[_dataOutputVideo setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
_session = [[AVCaptureSession alloc] init];
[_session addInput:deviceInput];
[_session addOutput:_dataOutput];
[_session addOutput:_dataOutputVideo];
// _session.sessionPreset = AVCaptureSessionPresetPhoto;
_session.sessionPreset = AVCaptureSessionPresetHigh;
// _session.sessionPreset = AVCaptureSessionPresetMedium;
[_session startRunning];
// add gesture
// UIGestureRecognizer *gr = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(didTapGesture:)];
// gr.delegate = self;
// [self.touchView addGestureRecognizer:gr];
_focusView = [[UIView alloc] init];
CGRect imageFrame = _focusView.frame;
imageFrame.size.width = 80;
imageFrame.size.height = 80;
_focusView.frame = imageFrame;
_focusView.center = CGPointMake(160, 202);
CALayer *layer = _focusView.layer;
layer.shadowOffset = CGSizeMake(2.5, 2.5);
layer.shadowColor = [[UIColor blackColor] CGColor];
layer.shadowOpacity = 0.5;
layer.borderWidth = 2;
layer.borderColor = [UIColor yellowColor].CGColor;
[self.touchView addSubview:_focusView];
_focusView.alpha = 0;
_isShowFlash = NO;
[self.view bringSubviewToFront:self.touchView];
UIView *footerView = [self.view viewWithTag:2];
[self.view bringSubviewToFront:footerView];
}
Later I am attaching to scroll view like this:
scrollImgView=[[UIImageView alloc]initWithFrame:CGRectMake(0, 0, 320, 340)];
UIImage *image = [UIImage imageWithData:appdelegate.capturedImgData];
UIImage *tempImage=[self resizeImage:image withWidth:320 withHeight:340];
NSData *imgData=UIImageJPEGRepresentation(tempImage,1.0);//0.25f
NSLog(#"image is %#",image);
scrollImgView.image=[UIImage imageWithData:imgData];
// scrollImgView.contentMode = UIViewContentModeScaleAspectFit;
// UIViewContentModeScaleAspectFit;
[postScrollView addSubview:scrollImgView];
Please give me suggestions if any one faced the same problem.

Answer 1

your coding is fine , and also is not a problem in in device, it may be occur
1. network problem
2. device memory is already loaded fully.
3. some Data conversation also taken times
here
UIImage *image = [UIImage imageWithData:appdelegate.capturedImgData];
UIImage *tempImage=[self resizeImage:image withWidth:320 withHeight:340]; //
NSData *imgData=UIImageJPEGRepresentation(tempImage,1.0);//0.25f
the above code u having used
1. data conversion is taken high and also taken the 2 time of image conversion optimize any `NSData`
2. third line is improve the `quality` of your image-- this also take the time for image conversion.
in my suggestion
1. use `Asychronous method`
-- sdwebimage
-- Asychronous Imageview
-- NSOperation_Queue
-- Dispatch im main_queue
use anyone of this , it will be taken the some response for you. in my suggestion is use SDWebImage.. use this link Loading takes a while when i set UIImage to a NSData with a url.

Answer 2

I solved the issue by changing
_session.sessionPreset = AVCaptureSessionPresetHigh to
_session.sessionPreset = AVCaptureSessionPresetMedium