Draw the content for a custom view.

Implement a drawRect: method in your custom view. Use your implementation of this method to draw content using paths, images, text, or any other tools available to you in Cocoa, Quartz, or OpenGL.

Update a custom view to reflect changed content.

Send a setNeedsDisplayInRect: or setNeedsDisplay: message to the view. Sending either of these messages marks part or all of the view as invalid and in need of an update. Cocoa responds by sending a drawRect: message to your view during the next update cycle.

Animate some content in a view.

Use Core Animation, set up a timer, or use the NSAnimation or NSViewAnimation classes, to generate notifications at a desired frame rate. Upon receiving the timer notification, invalidate part or all of your view to force an update. For information about Core Animation, see Core Animation Programming Guide. For more information about animating with timers, see “Using NSTimer for Animated Content.” For information about using NSAnimation objects, see “Using Cocoa Animation Objects.”

Draw during a live resize.

Use the inLiveResize method of NSView to determine if a live resize is happening. If it is, draw as little as possible while ensuring your view has the look you want. For more information about live resizing optimizations, see Drawing Performance Guidelines.

Draw during a printing operation.

Use the currentContextDrawingToScreen class method or isDrawingToScreen instance method of NSGraphicsContext to determine if a print operation is underway. Use the attributes method of NSGraphicsContext to retrieve (as needed) any additional information about the current print job. Draw images at the best possible resolution. Adjust your graphics in any other ways you think are appropriate to achieve the best possible appearance on the target device. For more information about printing, see Printing Programming Topics for Cocoa.

Create PDF or EPS data from a view.

Use the dataWithPDFInsideRect: or dataWithEPSInsideRect: method to obtain the data. In your drawRect: method use the currentContextDrawingToScreen class method or isDrawingToScreen instance method of NSGraphicsContext to determine if a print operation is underway.