SuperView | SuperView allows you to wrap your website in a super simple | iOS library

You ask:

How to properly allocate/initialize a weak variable?

You should:

1. Create your object with local variable:

I found the answer and have used Python for legibility.

View A is 1270*680.

I would recommend PDFAnnotation rather that UIView for adding content onto the PDFView.

It is not so easy to compare a UIView's frame within a PDFView due to their coordinate systems being different.

Adding a PDFAnnotation to the PDFView works in sync with the PDF coordinate system whereas working with UIView, you will need to do some conversions between coordinate spaces and this can be tricky and not so accurate.

Here are some small changes I made to kind of get this to work with a view.

First in your SignatoryXibView I added this function to show a red border when we are close to the edge

swift test only works for macOS testing. It does not support cross builds for iOS.

You do not need an existing Xcode project to use xcodebuild. Run the command, xcodebuild -list to initialize a Package.swift file for testing.

See the example here.

Fairly straightforward to do this with auto-layout / constraints...

We'll add var properties for Leading and Top constraints:

Here are a few thoughts and findings while playing around with this

1. Is the right scale factor being used?

The scaling you use is a bit custom and cannot be compared directly to the examples which has just 1 scale factor like 2 or 3. However, your scale factor has 2 dimensions but I see you compensate for this to get the minimum of the width and height scaling:

The problem is the absolute positioning of the logo. I see two ways:

1. scale the whole resulting image with .scaleEffect.
   Be aware this is a render scaling of the underlying image, it will not be redrawn in the new size, so can become blurry.

OK - so the problem is not with auto-layout...

The problem is that your code is setting the frame of your "bottomLine" layer incorrectly.

Most likely, you're calling your styleTextField() func in viewDidLoad(). However, UIKit has not set the frames of the views / UI elements yet.

You need to wait until the frames are set - such as in viewDidLayoutSubviews(). A new problem will crop up though, as that can be (and usually is) called multiple times, and your code would be creating and adding multiple "bottomLine" layers.

A better option would be to subclass UITextField and handle the layer frame in layoutSubviews().

Here's a quick sample:

I managed to figure it out after playing around for a good while. And I think I've had a feeling about what the the problem was all along...

Short answer: Do not try to animate views by changing their .frame or .bounds when using Auto Layout Constraints. Changing these properties might cause undefined behaviour (like the one I experienced). Instead, animate views by changing their constraints or the .center and/or .transform property. These properties do not conflict with the layout engine. When querying a view for its size, use the .bounds property, since this property is more reliable than .frame when using Auto Layout Constraints.

Slightly longer answer: Since I was using Auto Layout Constraints all over the place, combining it with manually changing the frames of views during animation did not work. Or more correct - had undefined behaviours. Since the Auto Layout Engine uses constraints to modify the view's frame for you, you should avoid touching the .frame (and .bounds) property yourself. Instead, animate your views by changing properties like .center and .transform. It seems like these properties do not conflict with Auto Layout, and changes to these properties will be applied to your views after the Auto Layout Engine has done its calculations. Event thought changing the .frame and .bounds of the view might work sometimes in combinations with Auto Layout Constraints, like I experienced with my custom presentation animation (which seemed to work flawlessly!), you should really avoid it. A workaround in some cases might be to temporary turn .translatesAutoresizingMaskIntoConstraints == true, but this is really not a god idea since it causes UIKit to generate Auto Layout Constraints for you, and those constraints might conflict with your own constraints. When querying a view for its size, use the .bounds property, since this property is more reliable than .frame when using Auto Layout Constraints and the .transform property.

Worthy mentions from the Apple documentation:

UIView.center:

Use this property, instead of the frame property, when you want to change the position of a view. The center point is always valid, even when scaling or rotation factors are applied to the view's transform. Changes to this property can be animated.

UIView.transform:

In iOS 8.0 and later, the transform property does not affect Auto Layout. Auto layout calculates a view’s alignment rectangle based on its untransformed frame.

Warning: When the value of this property is anything other than the identity transform, the value in the frame property is undefined and should be ignored.

UIView.translatesAutoresizingMaskIntoConstraints:

If this property’s value is true, the system creates a set of constraints that duplicate the behavior specified by the view’s autoresizing mask. This also lets you modify the view’s size and location using the view’s frame, bounds, or center properties, allowing you to create a static, frame-based layout within Auto Layout.

Note that the autoresizing mask constraints fully specify the view’s size and position; therefore, you cannot add additional constraints to modify this size or position without introducing conflicts. If you want to use Auto Layout to dynamically calculate the size and position of your view, you must set this property to false, and then provide a non ambiguous, nonconflicting set of constraints for the view.

By default, the property is set to true for any view you programmatically create. If you add views in Interface Builder, the system automatically sets this property to false.

For those interested, below is my final code for the custom UIViewControllerTransitioningDelegate. Only using Auto Layout Constraints, and only modifying the view properties mentioned above. Note: I'm using TinyConstraints to make writing constraints more pleasant.