Slides from the talk “Face Detection and Recognition for Fun and Profit” for XCake

These are the slides to my talk for XCake on using OpenCV for face recognition on iOS. It should be noted that the first half of the talk deals with using OpenCV to also detect faces and so applies to any platform you can use OpenCV on. The simplified code sample on slide 14 should more or less work for you on non-iOS implementations.


Slide 4:

Slide 6:

Slide 9:

Slide 10:

Slide 25:

Slide 27:


520 – What’s New in Camera Capture from WWDC 2012 talks about CIDetector and AVCaptureMetadataOutput from about the 19 minute mark. You should look at the sample code from that talk (StacheCam) for details on how to implement CIDetector and AVCaptureMedataOutput rather than the SquareCam project referenced in the Apple Documentation.

iOS 6, Auto Layout and MKMapView

I’m currently in the throws of updating an app for iOS 7. As part of the update, I’m throwing out all the XIBs and buying fully into using auto layout programatically.

I’ve been concentrating on getting it all to work on iOS 7 and only started at looking at how it looks on iOS 6 this week. Straight away I hit an issue

Auto Layout still required after executing -layoutSubviews. MKMapView's implementation of -layoutSubviews needs to call super.

The solution turns out to fairly straight forward. You don’t seem to be able to directly apply constraints between a MKMapView and another subview under iOS 6. Instead, you place your map into a container view and set the autoresizingMask to flexible width and height. You can then apply any constraints needed to the container view.

The code below simply creates a MKMapView which takes up the whole screen. From there, you could add buttons to the container view that are constrained to float 30 points from the bottom (which is what I needed to do).

self.mapContainerView = [[UIView alloc] initWithFrame:CGRectZero];
self.mapContainerView.translatesAutoresizingMaskIntoConstraints = NO;

self.mapView = [[MKMapView alloc] initWithFrame:self.mapContainerView.frame];
self.mapView.showsUserLocation = YES;
self.mapView.delegate = self;
self.mapView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
[self.mapContainerView addSubview:self.mapView];

[self.view addSubview:self.mapContainerView];

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"|[_mapContainerView]|" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_mapContainerView)]];

[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_mapContainerView]" options:0 metrics:nil views:NSDictionaryOfVariableBindings(_mapContainerView)]];

As an aside: Reveal has been invaluable in debugging my auto layout issues.