Added extension for UIView constrain center

Author: dharmik-yml

Sources/YCoreUI/Extensions/UIKit/UIView+constrainCenter.swift

@@ -0,0 +1,64 @@
+//
+//  UIView+constrainCenter.swift
+//  YCoreUI
+//
+//  Created by Dharmik Ghelani on 20/10/22.
+//  Copyright © 2022 Y Media Labs. All rights reserved.
+//
+
+import UIKit
+
+extension UIView {
+    /// Struct to define center attribute
+    struct Center: OptionSet {
+        let rawValue: UInt
+        static let x = Center(rawValue: 1 << 0)
+        static let y = Center(rawValue: 1 << 1)
+        static let all: Center = [.x, .y]
+    }
+    
+    /// Constrain the receiving view with provided center attributes
+    /// - Parameters:
+    ///   - center: Center attribute of view to constrain to (default `.all`)
+    ///   - view2: View object to which constrain to (pass `nil` to constrain to superview)
+    ///   - relation: Relation to evaluate (default `.equal`)
+    ///   - offset: Offset to apply to attribute(center X and Y) (default `.zero`)
+    ///   - priority: Constraint priority (default `.required`)
+    ///   - isActive: Whether to activate the constraint or not (default `true`)
+    /// - Returns: The created layout constraint
+    func constrainCenter(
+        _ center: Center = .all,
+        to view2: Anchorable? = nil,
+        relatedBy relation: NSLayoutConstraint.Relation = .equal,
+        offset: UIOffset = .zero,
+        priority: UILayoutPriority = .required,
+        isActive: Bool = true
+    ) -> [NSLayoutConstraint.Attribute: NSLayoutConstraint] {
+        var constraints: [NSLayoutConstraint.Attribute: NSLayoutConstraint] = [:]
+        let otherView: Anchorable! = view2 ?? superview
+        
+        if center.contains(.x) {
+            constraints[.centerX] = constrain(
+                .centerXAnchor,
+                to: otherView.centerXAnchor,
+                relatedBy: relation,
+                constant: offset.horizontal,
+                priority: priority,
+                isActive: isActive
+            )
+        }
+        
+        if center.contains(.y) {
+            constraints[.centerY] = constrain(
+                .centerYAnchor,
+                to: otherView.centerYAnchor,
+                relatedBy: relation,
+                constant: offset.vertical,
+                priority: priority,
+                isActive: isActive
+            )
+        }
+        
+        return constraints
+    }
+}

Tests/YCoreUITests/Extensions/UIKit/UIView+constrainCenterTests.swift

@@ -0,0 +1,84 @@
+//
+//  UIView+constrainCenterTests.swift
+//  YCoreUI
+//
+//  Created by Dharmik Ghelani on 20/10/22.
+//  Copyright © 2022 Y Media Labs. All rights reserved.
+//
+
+import XCTest
+@testable import YCoreUI
+
+final class UIViewConstrainCenterTests: XCTestCase {
+    func testCenterX() {
+        let (sut, offset) = makeSUT()
+        
+        let constraints = sut.view1.constrainCenter(.x, offset: offset)
+        let centerXConstraint = constraints[.centerX]
+        
+        XCTAssertFalse(sut.view1.translatesAutoresizingMaskIntoConstraints)
+        XCTAssertEqual(constraints.count, 1)
+        XCTAssertNotNil(centerXConstraint)
+        XCTAssertEqual(centerXConstraint?.firstItem as? UIView, sut.view1)
+        XCTAssertEqual(centerXConstraint?.firstAttribute, .centerX)
+        XCTAssertEqual(centerXConstraint?.secondItem as? UIView, sut)
+        XCTAssertEqual(centerXConstraint?.secondAttribute, .centerX)
+        XCTAssertEqual(centerXConstraint?.constant, offset.horizontal)
+    }
+    
+    func testCenterY() {
+        let (sut, offset) = makeSUT()
+        
+        let constraints = sut.view1.constrainCenter(.y, offset: offset)
+        let centerYConstraint = constraints[.centerY]
+        
+        XCTAssertFalse(sut.view1.translatesAutoresizingMaskIntoConstraints)
+        XCTAssertEqual(constraints.count, 1)
+        XCTAssertNotNil(centerYConstraint)
+        XCTAssertEqual(centerYConstraint?.firstItem as? UIView, sut.view1)
+        XCTAssertEqual(centerYConstraint?.firstAttribute, .centerY)
+        XCTAssertEqual(centerYConstraint?.secondItem as? UIView, sut)
+        XCTAssertEqual(centerYConstraint?.secondAttribute, .centerY)
+        XCTAssertEqual(centerYConstraint?.constant, offset.vertical)
+    }
+    
+    func testCenterBoth() {
+        let (sut, offset) = makeSUT()
+        
+        let constraints = sut.view1.constrainCenter(offset: offset)
+        
+        let anchorAttributes: [
+            (NSLayoutConstraint.Attribute, CGFloat)
+        ] = [
+            (.centerX, offset.horizontal),
+            (.centerY, offset.vertical)
+        ]
+        
+        XCTAssertFalse(sut.view1.translatesAutoresizingMaskIntoConstraints)
+        XCTAssertEqual(constraints.count, 2)
+        
+        anchorAttributes.forEach {
+            let constraint = constraints[$0.0]
+            XCTAssertNotNil(constraint)
+            XCTAssertEqual(constraint?.firstItem as? UIView, sut.view1)
+            XCTAssertEqual(constraint?.firstAttribute, $0.0)
+            XCTAssertEqual(constraint?.secondItem as? UIView, sut)
+            XCTAssertEqual(constraint?.secondAttribute, $0.0)
+            XCTAssertEqual(constraint?.constant, $0.1)
+        }
+    }
+}
+
+extension UIViewConstrainCenterTests {
+    func makeSUT(
+        file: StaticString = #filePath,
+        line: UInt = #line
+    ) -> (MockLayoutContainer, UIOffset) {
+        let container = MockLayoutContainer()
+        let offset = UIOffset(horizontal: 30, vertical: 20)
+        
+        trackForMemoryLeak(container, file: file, line: line)
+        
+        return (container, offset)
+    }
+}