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Controls
Control spacing: Leave 12 pixels between round buttons or between a round button and another interface element.
Round Button Implementation
Round buttons are available in Interface Builder. To create one using Application Kit programming interfaces, use the setBezelStyle: method of NSButtonCell with NSCircularBezelStyle as the argument.
Selection Controls
The controls described in the following sections provide ways for users to make selections from multiple items. Some selection controls allow only a single selection, others can be configured to allow a single selection or multiple selections.
Important: The controls described in this section are suitable for use in the window body; they should not be used in the window-frame areas. The single exception is the icon button with a pop-up menu, which can also be used in a toolbar. See “Window-Frame Controls” (page 249) for controls designed specifically for use in the toolbar and bottom-bar areas in your window.
Radio Buttons
A group of radio buttons provides users with a set of mutually exclusive, but related, choices. For example, Security preferences uses radio buttons to allow users to choose which connections can get through the firewall, as shown in Figure 15-20.
Figure 15-20 Radio buttons offer mutually exclusive choices
Radio buttons
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Radio Button Usage
Use a group of radio buttons when you need to display a set of choices from which the user can choose only one. If you need to display a set of choices from which the user can choose more than one at the same time, use checkboxes instead. Also, if you need to display a single setting, state, or choice the user can either accept or reject, don’t use a single radio button; instead you can use a checkbox. To learn more about checkboxes, see “Checkboxes” (page 275).
A group of radio buttons should contain at least two items and a maximum of about five. If you need to display more than five items, consider using a pop-up menu (described in “Pop-Up Menus” (page 281)).
A radio button should never initiate an action, although the choice of a radio button can change the state of the application. For example, Speech preferences allows the user to choose between two listening methods, as shown in Figure 15-21. If the user chooses the second listening method (“Listen continuously with keyword”), the keyword setup preferences are automatically enabled.
Figure 15-21 A radio button can change the state of an application
Selecting the other radio button enables the keyword controls
Radio Button Contents and Labeling
The selected and unselected appearances of a radio button are provided automatically; you cannot display any text or images in a radio button.
Radio buttons should be accompanied by text labels that describe the choice associated with each button. These labels should have sentence-style capitalization, as described in “Capitalization of Interface Element Labels and Text” (page 131).
A set of radio buttons is never dynamic; that is, the contents and labels shouldn’t change depending on the context.
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Radio Button Specifications
Control sizes: The dimensions of the radio button itself are fixed for each size, but you determine the length of the label that introduces the group and the length of each radio button label.
Label spacing and fonts: Radio button text (both the introductory label and control label) should be in a font that is proportional to the size of the control. The following fonts are supplied automatically by Interface Builder:
■Regular size: System font.
■Small: Small system font.
■Mini: Mini system font.
Use the following metrics to position the introductory labels correctly:
■Regular size: 8 pixels from the end of the label (the colon) to the control.
■Small: 6 pixels from the end of the label (the colon) to the control.
■Mini: 5 pixels from the end of the label (the colon) to the control.
Control spacing: Radio buttons can be arranged vertically or horizontally, depending on the overall layout of your window or dialog. Typically, however, radio buttons are stacked vertically to emphasize the mutually exclusive relationship among the buttons.
If you position a group of radio buttons horizontally, measure the space needed to accommodate the longest radio button label. Use that measurement to make the space between each pair of radio buttons consistent.
Use the following metrics when you position radio buttons vertically:
■Regular size: 6 pixels between controls.
■Small: 6 pixels between controls.
■Mini: 5 pixels between controls.
For radio buttons stacked vertically or horizontally, be sure to align the baseline of the introductory label with the baseline of the first button’s label, as shown in Figure 15-22.
Figure 15-22 Radio button label alignment
Align the baselines of the label and the first button's text
Radio Button Implementation
Radio buttons are available in Interface Builder. To create one using Application Kit programming interfaces, create an NSButton object with type NSRadioButton.
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2008-06-09 | © 1992, 2001-2003, 2008 Apple Inc. All Rights Reserved.