Sample code for creating a NSTextField “label”?

Question

In my desktop Mac OS X app, I\'d like to programatically create a NSTextField \"label\" which has the same behavior and properties as a typical label created in Interface Bu

Answer 1

Specifically, you will want to setBordered:NO, and set the bezel style to whatever that bezel style is which I forgot. Also setEditable:NO, and optionally setSelectable:NO. That should suffice.

Answer 2

A label is actually an instance of NSTextField, a subclass of NSView. So, since it is a NSView, it has to be added to another view.

Here's a working code:

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    NSTextField *textField;

    textField = [[NSTextField alloc] initWithFrame:NSMakeRect(10, 10, 200, 17)];
    [textField setStringValue:@"My Label"];
    [textField setBezeled:NO];
    [textField setDrawsBackground:NO];
    [textField setEditable:NO];
    [textField setSelectable:NO];
    [view addSubview:textField];
}

Answer 3

macOS 10.12 and Later

Starting with macOS 10.12 (Sierra), there are three new NSTextField constructors:

• NSTextField(labelWithString:), which the header file comment says “Creates a non-wrapping, non-editable, non-selectable text field that displays text in the default system font.”

• NSTextField(wrappingLabelWithString:), which the header file comment says “Creates a wrapping, non-editable, selectable text field that displays text in the default system font.”

• NSTextField(labelWithAttributedString:), which the header file comment says “Creates a non-editable, non-selectable text field that displays attributed text. The line break mode of this field is determined by the attributed string's NSParagraphStyle attribute.”

I tested the ones that take a plain (non-attributed string), and they create text fields that are similar to, but not precisely the same as, the text fields created in a storyboard or xib.

The important difference is that both constructors create a text field with textBackgroundColor (normally pure white) as its background color, while the storyboard text field uses controlColor (normally about 90% white).

Unimportantly, both constructors also set their fonts by calling NSFont.systemFont(ofSize: 0) (which produces a different NSFont object than my code below, but they wrap the same underlying Core Text font).

The wrappingLabelWithString: constructor sets the field's isSelectable to true. (This is documented in the header file.)

---

macOS 10.11 and Earlier

I compared four NSTextField instances: one created by dragging a “Label” to a storyboard, another created by dragging a “Wrapping Label” to a storyboard, and two in code. Then I carefully modified properties of the code-created labels until all their properties were exactly the same as the storyboard-created labels. These two methods are the result:

extension NSTextField {

    /// Return an `NSTextField` configured exactly like one created by dragging a “Label” into a storyboard.
    class func newLabel() -> NSTextField {
        let label = NSTextField()
        label.isEditable = false
        label.isSelectable = false
        label.textColor = .labelColor
        label.backgroundColor = .controlColor
        label.drawsBackground = false
        label.isBezeled = false
        label.alignment = .natural
        label.font = NSFont.systemFont(ofSize: NSFont.systemFontSize(for: label.controlSize))
        label.lineBreakMode = .byClipping
        label.cell?.isScrollable = true
        label.cell?.wraps = false
        return label
    }

    /// Return an `NSTextField` configured exactly like one created by dragging a “Wrapping Label” into a storyboard.
    class func newWrappingLabel() -> NSTextField {
        let label = newLabel()
        label.lineBreakMode = .byWordWrapping
        label.cell?.isScrollable = false
        label.cell?.wraps = true
        return label
    }

}

If you use one of these methods, don't forget to set your field's frame, or turn off its translatesAutoresizingMaskIntoConstraints and add constraints.

---

Here is the code I used to compare the different text fields, in case you want to check:

import Cocoa

class ViewController: NSViewController {

    @IBOutlet var label: NSTextField!
    @IBOutlet var multilineLabel: NSTextField!

    override func loadView() {
        super.loadView()
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        let codeLabel = NSTextField.newLabel()
        let codeMultilineLabel = NSTextField.newWrappingLabel()

        let labels = [label!, codeLabel, multilineLabel!, codeMultilineLabel]

        for keyPath in [
            "editable",
            "selectable",
            "allowsEditingTextAttributes",
            "importsGraphics",
            "textColor",
            "preferredMaxLayoutWidth",
            "backgroundColor",
            "drawsBackground",
            "bezeled",
            "bezelStyle",
            "bordered",
            "enabled",
            "alignment",
            "font",
            "lineBreakMode",
            "usesSingleLineMode",
            "formatter",
            "baseWritingDirection",
            "allowsExpansionToolTips",
            "controlSize",
            "highlighted",
            "continuous",
            "cell.opaque",
            "cell.controlTint",
            "cell.backgroundStyle",
            "cell.interiorBackgroundStyle",
            "cell.scrollable",
            "cell.truncatesLastVisibleLine",
            "cell.wraps",
            "cell.userInterfaceLayoutDirection"
        ] {
            Swift.print(keyPath + " " + labels.map({ ($0.value(forKeyPath: keyPath) as? NSObject)?.description ?? "nil" }).joined(separator: " "))
        }
    }
}

Answer 4

Disassembled AppKit in Objective-C:

BOOL TMPSierraOrLater() {
    static BOOL result = NO;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        result = [NSProcessInfo.processInfo isOperatingSystemAtLeastVersion:(NSOperatingSystemVersion){ 10, 12, 0 }];
    });
    return result;
}

@implementation NSTextField (TMP)

+ (instancetype)TMP_labelWithString:(NSString *)stringValue {
    if (TMPSierraOrLater()) {
        return [self labelWithString:stringValue];
    }
    NSParameterAssert(stringValue);
    NSTextField *label = [NSTextField TMP_newBaseLabelWithoutTitle];
    label.lineBreakMode = NSLineBreakByClipping;
    label.selectable = NO;
    [label setContentHuggingPriority:(NSLayoutPriorityDefaultLow + 1) forOrientation:NSLayoutConstraintOrientationHorizontal];
    [label setContentHuggingPriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationVertical];
    [label setContentCompressionResistancePriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationHorizontal];
    [label setContentCompressionResistancePriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationVertical];
    label.stringValue = stringValue;
    [label sizeToFit];
    return label;
}

+ (instancetype)TMP_wrappingLabelWithString:(NSString *)stringValue {
    if (TMPSierraOrLater()) {
        return [self wrappingLabelWithString:stringValue];
    }
    NSParameterAssert(stringValue);
    NSTextField *label = [NSTextField TMP_newBaseLabelWithoutTitle];
    label.lineBreakMode = NSLineBreakByWordWrapping;
    label.selectable = YES;
    [label setContentHuggingPriority:NSLayoutPriorityDefaultLow forOrientation:NSLayoutConstraintOrientationHorizontal];
    [label setContentHuggingPriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationVertical];
    [label setContentCompressionResistancePriority:NSLayoutPriorityDefaultLow forOrientation:NSLayoutConstraintOrientationHorizontal];
    [label setContentCompressionResistancePriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationVertical];
    label.stringValue = stringValue;
    label.preferredMaxLayoutWidth = 0;
    [label sizeToFit];
    return label;
}

+ (instancetype)TMP_labelWithAttributedString:(NSAttributedString *)attributedStringValue {
    if (CRKSierraOrLater()) {
        return [self labelWithAttributedString:attributedStringValue];
    }
    NSParameterAssert(attributedStringValue);
    NSTextField *label = [NSTextField TMP_newBaseLabelWithoutTitle];
    [label setContentHuggingPriority:NSLayoutPriorityDefaultLow forOrientation:NSLayoutConstraintOrientationHorizontal];
    [label setContentHuggingPriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationVertical];
    [label setContentCompressionResistancePriority:NSLayoutPriorityDefaultLow forOrientation:NSLayoutConstraintOrientationHorizontal];
    [label setContentCompressionResistancePriority:NSLayoutPriorityDefaultHigh forOrientation:NSLayoutConstraintOrientationVertical];
    label.attributedStringValue = attributedStringValue;
    [label sizeToFit];
    return label;
}

#pragma mark - Private API

+ (instancetype)TMP_newBaseLabelWithoutTitle {
    NSTextField *label = [[self alloc] initWithFrame:CGRectZero];
    label.textColor = NSColor.labelColor;
    label.font = [NSFont systemFontOfSize:0.0];
    label.alignment = NSTextAlignmentNatural;
    label.baseWritingDirection = NSWritingDirectionNatural;
    label.userInterfaceLayoutDirection = NSApp.userInterfaceLayoutDirection;
    label.enabled = YES;
    label.bezeled = NO;
    label.bordered = NO;
    label.drawsBackground = NO;
    label.continuous = NO;
    label.editable = NO;
    return label;
}

@end

Answer 5

You could try using nib2objc to get all the properties that IB sets

Answer 6

This can be tricky to get right. I don't have the recipe for an exact replica handy, but when I've been stuck in a similar situation, here's what I do:

1. Create a UI element in IB.
2. Add an outlet to it from my controller class.
3. Break in gdb in awakeFromNib or whatever.
4. From the gdb prompt, "p *whateverOutlet" ... this will show you the C struct contents of the label NSTextField that IB set up.

By looking at all the myriad values in there, you can get a lot of guesses about what you're neglecting to set. Usually it ends up being some magic combination of bezel and border settings, that gets you where you want to be.