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rolfbjarne merged 2 commits into from
Dec 15, 2025
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[Foundation] Fix nullability in NSLayoutConstraint. #24434

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dd5955d
[Foundation] Fix nullability in NSLayoutConstraint.
web-flow Dec 9, 2025
43da3aa
Update src/Foundation/NSLayoutConstraint.cs
rolfbjarne Dec 15, 2025
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45 changes: 0 additions & 45 deletions docs/api/UIKit/NSLayoutConstraint.xml
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Original file line number Diff line number Diff line change
Expand Up @@ -31,25 +31,6 @@ var tconstraint1 = NSLayoutConstraint.Create (toolbar, NSLayoutAttribute.Width,
</remarks>
<related type="externalDocumentation" href="https://developer.apple.com/library/ios/documentation/AppKit/Reference/NSLayoutConstraint_Class/index.html">Apple documentation for <c>NSLayoutConstraint</c></related>
</Docs>
<Docs DocId="M:UIKit.NSLayoutConstraint.FromVisualFormat(System.String,UIKit.NSLayoutFormatOptions,System.Object[])">
<param name="format">Visual format to use to create the constraints.</param>
<param name="formatOptions">options.</param>
<param name="viewsAndMetrics">
<para>Pairs of names and values. The names should be strings (or NSStrings) and the values should be either UIViews, numbers (any C# number or NSNumber) or <see cref="ObjCRuntime.INativeObject" /> instances that are suitable to be passed to the underlying engine. </para>
<para>
</para>
<para> This binds the provided name with the view or binds the name with the number as a metric.</para>
</param>
<summary>Factory method for creating a constraint using Visual Format Language.</summary>
<returns>An array of layout constraints that are suitable to be added to a <see cref="View" /> using <see cref="View.AddConstraints(NSLayoutConstraint[])" /> method.</returns>
<remarks>
<example>
<code lang="csharp lang-csharp"><![CDATA[
NSLayoutConstraint.FromVisualFormat ("|-8-[messageView]-8-|", NSLayoutOptions.None, "messageView", MakeMessageView ());
]]></code>
</example>
</remarks>
</Docs>
<Docs DocId="M:UIKit.NSLayoutConstraint.ActivateConstraints(UIKit.NSLayoutConstraint[])">
<param name="constraints">Constraints to activate.</param>
<summary>Activates all of the constraints passed.</summary>
Expand Down Expand Up @@ -93,32 +74,6 @@ NSLayoutConstraint.ActivateConstraints(blueConstraints);
<para>It is easier to use the <see cref="NSLayoutConstraint.FromVisualFormat(System.String,NSLayoutFormatOptions,System.Object[])" /> overload as it combines support for both metrics and views in a single call.</para>
</remarks>
</Docs>
<Docs DocId="M:UIKit.NSLayoutConstraint.Create(Foundation.NSObject,UIKit.NSLayoutAttribute,UIKit.NSLayoutRelation,Foundation.NSObject,UIKit.NSLayoutAttribute,System.Runtime.InteropServices.NFloat,System.Runtime.InteropServices.NFloat)">
<param name="view1">First view in the constraint.</param>
<param name="attribute1">Attribute for the first view.</param>
<param name="relation">Relationships between the <paramref name="view1" /> and the <paramref name="view2" />.</param>
<param name="view2">
<para>Second view in the constraint.</para>
<para>This parameter can be <see langword="null" />.</para>
<para tool="nullallowed">This parameter can be <see langword="null" />.</para>
</param>
<param name="attribute2">Attribute for the second view.</param>
<param name="multiplier">Multiplier applied to the second attribute.</param>
<param name="constant">Constants to add.</param>
<summary>Factory method for creating a constraint.</summary>
<returns>
<para>New constraint with the specified parameters.</para>
<para>
</para>
</returns>
<remarks>
<para>Creates a constraint relationship between the <paramref name="view1" /> and the <paramref name="view2" /> that satisfies the following linear equation:</para>
<para>
</para>
<para>
<paramref name="attribute1" /> = <paramref name="multiplier" /> x <paramref name="attribute2" /> + <paramref name="constant" /></para>
</remarks>
</Docs>
<Docs DocId="M:UIKit.NSLayoutConstraint.Create(ObjCRuntime.INativeObject,UIKit.NSLayoutAttribute,UIKit.NSLayoutRelation,ObjCRuntime.INativeObject,UIKit.NSLayoutAttribute,System.Runtime.InteropServices.NFloat,System.Runtime.InteropServices.NFloat)">
<param name="view1">First view in the constraint.</param>
<param name="attribute1">Attribute for the first view.</param>
Expand Down
99 changes: 57 additions & 42 deletions src/Foundation/NSLayoutConstraint.cs
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Original file line number Diff line number Diff line change
@@ -1,10 +1,10 @@
//
// Helper functions to make FromVisualLayout more palattable
// Helper functions to make FromVisualFormat more palatable
//
// Author:
// Miguel de Icaza
//
// Copyright 2014 Xamarin INc
// Copyright 2014 Xamarin Inc
//

#if MONOMAC
Expand All @@ -13,8 +13,7 @@
using View = UIKit.UIView;
#endif

// Disable until we get around to enable + fix any issues.
#nullable disable
#nullable enable

#if MONOMAC
namespace AppKit
Expand All @@ -23,7 +22,7 @@ namespace UIKit
#endif
{
public partial class NSLayoutConstraint {
static NSNumber AsNumber (object o)
static NSNumber? AsNumber (object o)
{
if (o is NSNumber) return (NSNumber) o;
if (o is double) return new NSNumber ((double) o);
Expand All @@ -42,10 +41,26 @@ static NSNumber AsNumber (object o)
return null;
}

/// <include file="../../docs/api/UIKit/NSLayoutConstraint.xml" path="/Documentation/Docs[@DocId='M:UIKit.NSLayoutConstraint.FromVisualFormat(System.String,UIKit.NSLayoutFormatOptions,System.Object[])']/*" />
/// <summary>Factory method for creating a constraint using Visual Format Language.</summary>
/// <param name="format">Visual format to use to create the constraints.</param>
/// <param name="formatOptions">Options for the format.</param>
/// <param name="viewsAndMetrics">
/// <para>Pairs of names and values. The names should be strings (or <see cref="Foundation.NSString" />) and the values should be either <see cref="View" />s, numbers (any C# number or <see cref="Foundation.NSNumber" />) or <see cref="ObjCRuntime.INativeObject" /> instances that are suitable to be passed to the underlying engine.</para>
/// <para>This binds the provided name with the view or binds the name with the number as a metric.</para>
/// </param>
/// <returns>An array of layout constraints that are suitable to be added to a <see cref="View" /> using the <see cref="View.AddConstraints" /> method.</returns>
/// <remarks>
/// <example>
/// <code lang="csharp lang-csharp"><![CDATA[
/// NSLayoutConstraint.FromVisualFormat ("|-8-[messageView]-8-|", NSLayoutFormatOptions.None, "messageView", MakeMessageView ());
/// ]]></code>
/// </example>
/// </remarks>
static public NSLayoutConstraint [] FromVisualFormat (string format, NSLayoutFormatOptions formatOptions, params object [] viewsAndMetrics)
{
NSMutableDictionary views = null, metrics = null;
ArgumentNullException.ThrowIfNull (format);
ArgumentNullException.ThrowIfNull (viewsAndMetrics);
NSMutableDictionary? views = null, metrics = null;
var count = viewsAndMetrics.Length;
if (count != 0) {
if ((count % 2) != 0)
Expand Down Expand Up @@ -102,60 +117,60 @@ static public NSLayoutConstraint [] FromVisualFormat (string format, NSLayoutFor
return FromVisualFormat (format, formatOptions, metrics, views);
}

/// <param name="view1">To be added.</param>
/// <param name="attribute1">To be added.</param>
/// <param name="relation">To be added.</param>
/// <param name="multiplier">To be added.</param>
/// <param name="constant">To be added.</param>
/// <summary>Static factory method for creating a constraint.</summary>
/// <returns>To be added.</returns>
/// <remarks>To be added.</remarks>
/// <summary>Factory method for creating a constraint.</summary>
/// <param name="view1">The view or object in the constraint.</param>
/// <param name="attribute1">The attribute for the view.</param>
/// <param name="relation">The relationship in the constraint.</param>
/// <param name="multiplier">The multiplier applied to the attribute.</param>
/// <param name="constant">The constant value in the constraint.</param>
/// <returns>A new constraint with the specified parameters.</returns>
/// <remarks>Creates a constraint for a single view with a specified attribute, relation, multiplier, and constant value.</remarks>
public static NSLayoutConstraint Create (NSObject view1, NSLayoutAttribute attribute1, NSLayoutRelation relation, nfloat multiplier, nfloat constant)
{
return NSLayoutConstraint.Create (view1, attribute1, relation, null, NSLayoutAttribute.NoAttribute, multiplier, constant);
}

/// <param name="view1">To be added.</param>
/// <param name="attribute1">To be added.</param>
/// <param name="relation">To be added.</param>
/// <summary>Static factory method to create a constraint based on a <see cref="View" />, an <see cref="NSLayoutAttribute" />, and an <see cref="NSLayoutRelation" />.</summary>
/// <returns>To be added.</returns>
/// <remarks>To be added.</remarks>
/// <summary>Factory method to create a constraint based on a <see cref="View" />, an <see cref="NSLayoutAttribute" />, and an <see cref="NSLayoutRelation" />.</summary>
/// <param name="view1">The view or object in the constraint.</param>
/// <param name="attribute1">The attribute for the view.</param>
/// <param name="relation">The relationship in the constraint.</param>
/// <returns>A new constraint with the specified parameters and default multiplier (1.0) and constant (0.0).</returns>
/// <remarks>Creates a constraint for a single view with default multiplier and constant values.</remarks>
public static NSLayoutConstraint Create (NSObject view1, NSLayoutAttribute attribute1, NSLayoutRelation relation)
{
return NSLayoutConstraint.Create (view1, attribute1, relation, null, NSLayoutAttribute.NoAttribute, 1.0f, 0f);
}

// This solves the duplicate selector export problem while not breaking the API.
/// <include file="../../docs/api/UIKit/NSLayoutConstraint.xml" path="/Documentation/Docs[@DocId='M:UIKit.NSLayoutConstraint.Create(Foundation.NSObject,UIKit.NSLayoutAttribute,UIKit.NSLayoutRelation,Foundation.NSObject,UIKit.NSLayoutAttribute,System.Runtime.InteropServices.NFloat,System.Runtime.InteropServices.NFloat)']/*" />
/// <summary>Factory method for creating a constraint.</summary>
/// <param name="view1">First view in the constraint.</param>
/// <param name="attribute1">Attribute for the first view.</param>
/// <param name="relation">Relationship between the <paramref name="view1" /> and the <paramref name="view2" />.</param>
/// <param name="view2">Second view in the constraint. This parameter can be <see langword="null" />.</param>
/// <param name="attribute2">Attribute for the second view.</param>
/// <param name="multiplier">Multiplier applied to the second attribute.</param>
/// <param name="constant">Constant to add.</param>
/// <returns>A new constraint with the specified parameters.</returns>
/// <remarks>Creates a constraint relationship between the <paramref name="view1" /> and the <paramref name="view2" /> that satisfies the following linear equation: <paramref name="attribute1" /> = <paramref name="multiplier" /> x <paramref name="attribute2" /> + <paramref name="constant" />.</remarks>
public static NSLayoutConstraint Create (NSObject view1, NSLayoutAttribute attribute1, NSLayoutRelation relation,
NSObject view2, NSLayoutAttribute attribute2, nfloat multiplier, nfloat constant)
NSObject? view2, NSLayoutAttribute attribute2, nfloat multiplier, nfloat constant)
{
return Create ((INativeObject) view1, attribute1, relation, view2, attribute2, multiplier, constant);
}

/// <typeparam name="AnchorType">To be added.</typeparam>
/// <summary>For an anchor-based constraint, returns the first anchor, properly downcast to <c>AnchorType</c>.</summary>
/// <returns>To be added.</returns>
/// <remarks>To be added.</remarks>
[SupportedOSPlatform ("ios")]
[SupportedOSPlatform ("maccatalyst")]
[SupportedOSPlatform ("tvos")]
[SupportedOSPlatform ("macos")]
public NSLayoutAnchor<AnchorType> FirstAnchor<AnchorType> () where AnchorType : NSObject
/// <summary>For an anchor-based constraint, returns the first anchor, properly downcast to <typeparamref name="AnchorType" />.</summary>
/// <typeparam name="AnchorType">The type of anchor to return.</typeparam>
/// <returns>The first anchor of the constraint, cast to the specified anchor type.</returns>
/// <remarks>This method is useful for retrieving the first anchor when working with anchor-based constraints.</remarks>
public NSLayoutAnchor<AnchorType>? FirstAnchor<AnchorType> () where AnchorType : NSObject
{
return Runtime.GetNSObject<NSLayoutAnchor<AnchorType>> (_FirstAnchor ());
}

/// <typeparam name="AnchorType">To be added.</typeparam>
/// <summary>For an anchor-based constraint, returns the second anchor, properly downcast to <c>AnchorType</c>.</summary>
/// <returns>To be added.</returns>
/// <remarks>To be added.</remarks>
[SupportedOSPlatform ("ios")]
[SupportedOSPlatform ("maccatalyst")]
[SupportedOSPlatform ("tvos")]
[SupportedOSPlatform ("macos")]
public NSLayoutAnchor<AnchorType> SecondAnchor<AnchorType> () where AnchorType : NSObject
/// <summary>For an anchor-based constraint, returns the second anchor, properly downcast to <typeparamref name="AnchorType" />.</summary>
/// <typeparam name="AnchorType">The type of anchor to return.</typeparam>
/// <returns>The second anchor of the constraint, cast to the specified anchor type.</returns>
/// <remarks>This method is useful for retrieving the second anchor when working with anchor-based constraints.</remarks>
public NSLayoutAnchor<AnchorType>? SecondAnchor<AnchorType> () where AnchorType : NSObject
{
return Runtime.GetNSObject<NSLayoutAnchor<AnchorType>> (_SecondAnchor ());
}
Expand Down
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