Instance Property

clearsContextBeforeDrawing

A Boolean value that determines whether the view’s bounds should be automatically cleared before drawing.

Declaration

@property(nonatomic) BOOL clearsContextBeforeDrawing;

Discussion

When set to YES, the drawing buffer is automatically cleared to transparent black before the drawRect: method is called. This behavior ensures that there are no visual artifacts left over when the view’s contents are redrawn. If the view’s opaque property is also set to YES, the backgroundColor property of the view must not be nil or drawing errors may occur. The default value of this property is YES.

If you set the value of this property to NO, you are responsible for ensuring the contents of the view are drawn properly in your drawRect: method. If your drawing code is already heavily optimized, setting this property is NO can improve performance, especially during scrolling when only a portion of the view might need to be redrawn.

See Also

Configuring a View’s Visual Appearance

backgroundColor

The view’s background color.

hidden

A Boolean value that determines whether the view is hidden.

alpha

The view’s alpha value.

opaque

A Boolean value that determines whether the view is opaque.

tintColor

The first nondefault tint color value in the view’s hierarchy, ascending from and starting with the view itself.

tintAdjustmentMode

The first non-default tint adjustment mode value in the view’s hierarchy, ascending from and starting with the view itself.

clipsToBounds

A Boolean value that determines whether subviews are confined to the bounds of the view.

maskView

An optional view whose alpha channel is used to mask a view’s content.

layerClass

Returns the class used to create the layer for instances of this class.

layer

The view’s Core Animation layer used for rendering.