A visual representation of a level or quantity, using discrete values.


@interface NSLevelIndicator : NSControl


A level indicator is similar to an NSSlider object, but provides a more customized visual feedback to the user. Unlike sliders, level indicators do not have a “knob” indicating the current setting, and they do not allow the user to adjust the current setting. You set the value of the level indicator programmatically. The supported indicator styles include:

  • A capacity style level indicator. The continuous mode for this style is often used to indicate conditions such as how much data is on hard disk. The discrete mode is similar to audio level indicators in audio playback applications. You can specify both a warning value and a critical value that provides additional visual feedback to the user.

  • A ranking style level indicator. This is similar to the star ranking displays provided in iTunes and iPhoto. You can also specify your own ranking image.

  • A relevancy style level indicator. This style is used to display the relevancy of a search result, for example in Mail.

NSLevelIndicator uses an NSLevelIndicatorCell to implement much of the control’s functionality. NSLevelIndicator provides cover methods for most of the NSLevelIndicatorCell methods, which call the corresponding cell method.


Configuring the Cell


NSLevelIndicatorCell is a subclass of NSActionCell that provides several level indicator display styles including: capacity, ranking and relevancy. The capacity style provides both continuous and discrete modes.

Configuring the Range of Values


The receiver’s minimum value.


The receiver’s maximum value.


The receiver’s warning value.


The receiver’s critical value.

Managing Tick Marks and Style


Determines how the receiver’s tick marks are aligned with it.


The number of tick marks associated with the receiver.


The number of major tick marks associated with the receiver.

- tickMarkValueAtIndex:

Returns the receiver’s value represented by the tick mark at the specified index (the minimum-value tick mark has an index of 0).

- rectOfTickMarkAtIndex:

Returns the bounding rectangle of the tick mark identified by the specified index (the minimum-value tick mark is at index 0).


The appearance of the indicator.


Constants that specify a level indicator's appearance.

Controlling the Edit Behavior


Inherits From

See Also



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