A Boolean value that determines whether the view is opaque.
- iOS 2.0+
- tvOS 9.0+
This property provides a hint to the drawing system as to how it should treat the view. If set to
true, the drawing system treats the view as fully opaque, which allows the drawing system to optimize some drawing operations and improve performance. If set to
false, the drawing system composites the view normally with other content. The default value of this property is
An opaque view is expected to fill its bounds with entirely opaque content—that is, the content should have an alpha value of
1. If the view is opaque and either does not fill its bounds or contains wholly or partially transparent content, the results are unpredictable. You should always set the value of this property to
false if the view is fully or partially transparent.
You only need to set a value for the opaque property in subclasses of
UIView that draw their own content using the
draw(_:) method. The opaque property has no effect in system-provided classes such as
UITable, and so on.