When should I call layoutSubviews?

Published by Charlie Davidson on

When should I call layoutSubviews?

A change in bounds of a view that is not yet in a view hierarchy will result in a call to layoutSubviews: when the view is eventually added to a view hierarchy. And just for completeness: these triggers do not directly call layoutSubviews, but rather call setNeedsLayout , which sets/raises a flag.

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.

When should I call layoutIfNeeded?

You should call layoutIfNeeded before the start of an animation block to ensure all layout updates are propagated before the start of the animation. Configure your new constraints, then inside the animation block, call layoutIfNeeded again to animate to the new state.

How do I override layoutSubviews?

When overriding layoutSubviews : Make sure to call super. layoutSubviews() . Don’t call setNeedsLayout or setNeedsUpdateConstraints , otherwise an infinite loop will be created.

What triggers layoutSubviews?

addSubview: causes layoutSubviews to be called on the view being added, the view it’s being added to (target view), and all the subviews of the target. view setFrame intelligently calls layoutSubviews on the view having its frame set only if the size parameter of the frame is different.

What is the difference between layoutIfNeeded () and setNeedsLayout ()?

The reason being layoutIfNeeded() forces the view to update immediately, while setNeedsLayout() only updates the view when the animation cycle comes.

Should I call super layoutSubviews?

You always have to call [super layoutSubviews] last, if the intrinsic content size of a view will be changed. If you change the title of the button, the intrinsic content size of the UIButton will be changed, therefore the last call.

What is layoutSubviews in Swift?

— layoutSubviews() 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. You can use your implementation to set the frame rectangles of your subviews directly.

Does setNeedsLayout call layoutSubviews?

What is layer Swift?

Overview. Layers are often used to provide the backing store for views but can also be used without a view to display content. A layer’s main job is to manage the visual content that you provide but the layer itself has visual attributes that can be set, such as a background color, border, and shadow.

What is UIView in Swift?

The UIView class is a concrete class that you can instantiate and use to display a fixed background color. You can also subclass it to draw more sophisticated content. Views draw content in their rectangular area using UIKit or Core Graphics. You can animate some view properties to new values.

What’s the difference between a cell and a uitableviewcell?

A UITableViewCell object is a specialized type of view that manages the content of a single table row. You use cells primarily to organize and present your app’s custom content, but UITableViewCell provides some specific customizations to support table-related behaviors, including: Applying a selection or highlight color to the cell.

How to create cell objects in Table View?

Using Cell Objects in Predefined Styles Using the UITableViewCellclass directly, you can create“off-the-shelf” cell objects in a range of predefined styles. Standard Styles for Table View Cellsdescribes these standard cells and provides examples of how they look in a table view.

What kind of content does a table view cell have?

UITableViewCellStyleSubtitle } UITableViewCellStyle; These cell objects have two kinds of content: one or more text strings and, in some cases, an image. Figure 5-3shows the approximate areas for image and text. As an image expands to the right, it pushes the text in the same direction.

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