When should I use layoutSubviews?
layoutSubviews() The system calls this method whenever it needs to recalculate the frames of views, so you should override it when you want to set frames and specify positioning and sizing. However, you should never call this explicitly when your view hierarchy requires a layout refresh.
How often is layoutSubviews called?
layoutSubviews is called when the view is created, but never again. My subviews are correctly laid out. If I toggle the in-call status bar off, the subview’s layoutSubviews is not called at all, even though the main view does animate its resize.
How do I force layoutSubviews?
If you want to force a layout update, call the setNeedsLayout() method instead to do so prior to the next drawing update. If you want to update the layout of your views immediately, call the layoutIfNeeded() method.
What is responder chain?
The responder chain is a series of linked responder objects. It starts with the first responder and end with the app object. If the first responder cannot handle an event, it forwards the event to the next responder in the responder chain. A responder object is an object that can respond to and handle events.
Should I call layoutIfNeeded?
LayoutIfNeeded() – Layout subviews immediately. Show activity on this post. setNeedsLayout actually calls layoutIfNeeded, so if your calling setNeedsDisplay there’s no reason to call layoutIfNeeded. In this way setNeedsLayout is a convenience method for calling layoutIfNeeded which does the heavy lifting.
What is UIView life cycle?
Every UIView with enabled Auto Layout passes 3 steps after initialization: update, layout and render. These steps do not occur in a one-way direction. It’s possible for a step to trigger any previous one or even force the whole cycle to repeat.
What is preferredContentSize?
The preferredContentSize allows a child view controller to tell a parent container view controller the size it wants to be. In this case the parent container view is a popover presentation controller.
What is sizeToFit?
iOS UILabel Size to fit To make the changes easily visible, change the backgroundColor and textColor of labelOne in the viewDidLoad method: The function sizeToFit is used when you want to automatically resize a label based on the content stored within it.
What is Uievent?
An object that describes a single user interaction with your app.
What is setNeedsLayout?
setNeedsLayout() Invalidates the current layout of the receiver and triggers a layout update during the next update cycle.
What is Nslayoutconstraint?
The relationship between two user interface objects that must be satisfied by the constraint-based layout system.
What does Documentation call the parent view that’s embedding the other view?
Embedding one view inside another creates a containment relationship between the host view (known as the superview) and the embedded view (known as the subview).
What is responder chain iOS?
In iOS, the Responder Chain is the name given to an UIKit-generated linked list of UIResponder objects, and is the foundation for everything regarding events (like touch and motion) in iOS.
When is layoutsubviews called on a view?
I found that layoutSubviews: will be called on a view if and only if: Its own bounds (not frame) changed. The bounds of one of its direct subviews changed. A subview is added to the view or removed from the view. The bounds are considered changed only if the new value is different, including a different origin.
What is the default implementation of the subview () method?
The default implementation of this method does nothing on iOS 5.1 and earlier. Otherwise, the default implementation uses any constraints you have set to determine the size and position of any subviews. Subclasses can override this method as needed to perform more precise layout of their subviews.
Why is layoutsubviews called when a UIScrollView scroll?
Note specifically that is why layoutSubviews: is called whenever a UIScrollView scrolls, as it performs the scrolling by changing its bounds’ origin. Changing the frame will only change the bounds if the size has changed, as this is the only thing propagated to the bounds property.
How do I set the frame rectangles of my subviews?
You can use your implementation to set the frame rectangles of your subviews directly. You should not call this method directly. If you want to force a layout update, call the setNeedsLayout () method instead to do so prior to the next drawing update. If you want to update the layout of your views immediately, call the layoutIfNeeded () method.