Add ability to filter randomly selected gradients

Sources/.swiftlint.yml

@@ -0,0 +1,23 @@
+disabled_rules:
+- trailing_whitespace
+- vertical_whitespace
+- line_length
+- opening_brace
+- large_tuple
+- generic_type_name
+- multiple_closures_with_trailing_closure
+
+opt_in_rules:
+- closure_spacing
+- conditional_returns_on_newline
+#- empty_count
+- explicit_init
+#- force_unwrapping // THIS SHOULD BE USED
+#- missing_docs
+- overridden_super_call
+- private_outlet
+- redundant_nil_coalesing
+#- switch_case_on_newline
+
+excluded:
+- gen

Sources/Randient.xcodeproj/project.pbxproj

@@ -13,11 +13,12 @@
 		464BE4E321455020009B2A0D /* Randient.swift in Sources */ = {isa = PBXBuildFile; fileRef = 464BE4E221455020009B2A0D /* Randient.swift */; };
 		468EE01C2166A5A400C27982 /* RandientTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 468EE01B2166A5A400C27982 /* RandientTests.swift */; };
 		468EE01E2166A5A400C27982 /* Randient.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 4639DD4C21451CFA0038E5A6 /* Randient.framework */; };
-		46DBB9CE21516B290094B965 /* UIGradient+Metadata.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46DBB9CD21516B290094B965 /* UIGradient+Metadata.swift */; };
 		46DBB9D8215173D40094B965 /* UIColor+Analysis.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46DBB9D4215173D40094B965 /* UIColor+Analysis.swift */; };
 		46DBB9D9215173D40094B965 /* RandientView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46DBB9D6215173D40094B965 /* RandientView.swift */; };
 		46DBB9DA215173D40094B965 /* GradientView.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46DBB9D7215173D40094B965 /* GradientView.swift */; };
 		46DBB9DC215173E40094B965 /* UIColor+Interpolation.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46DBB9DB215173E40094B965 /* UIColor+Interpolation.swift */; };
+		46E057A42175F2F1003FB809 /* UIGradientFilter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46E057A22175F2F1003FB809 /* UIGradientFilter.swift */; };
+		46E057A52175F2F1003FB809 /* UIGradient+Metadata.swift in Sources */ = {isa = PBXBuildFile; fileRef = 46E057A32175F2F1003FB809 /* UIGradient+Metadata.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -40,11 +41,12 @@
 		468EE0192166A5A400C27982 /* RandientTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = RandientTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		468EE01B2166A5A400C27982 /* RandientTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RandientTests.swift; sourceTree = "<group>"; };
 		468EE01D2166A5A400C27982 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
-		46DBB9CD21516B290094B965 /* UIGradient+Metadata.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UIGradient+Metadata.swift"; sourceTree = "<group>"; };
 		46DBB9D4215173D40094B965 /* UIColor+Analysis.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "UIColor+Analysis.swift"; sourceTree = "<group>"; };
 		46DBB9D6215173D40094B965 /* RandientView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = RandientView.swift; sourceTree = "<group>"; };
 		46DBB9D7215173D40094B965 /* GradientView.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = GradientView.swift; sourceTree = "<group>"; };
 		46DBB9DB215173E40094B965 /* UIColor+Interpolation.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UIColor+Interpolation.swift"; sourceTree = "<group>"; };
+		46E057A22175F2F1003FB809 /* UIGradientFilter.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = UIGradientFilter.swift; sourceTree = "<group>"; };
+		46E057A32175F2F1003FB809 /* UIGradient+Metadata.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "UIGradient+Metadata.swift"; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -98,7 +100,7 @@
 			children = (
 				4639DD4F21451CFA0038E5A6 /* Randient.h */,
 				464BE4E221455020009B2A0D /* Randient.swift */,
-				46DBB9CD21516B290094B965 /* UIGradient+Metadata.swift */,
+				46E057A12175F2F1003FB809 /* Gradient */,
 				46DBB9D5215173D40094B965 /* Views */,
 				46DBB9D3215173D40094B965 /* Extensions */,
 				4639DD5021451CFA0038E5A6 /* Info.plist */,
@@ -134,6 +136,15 @@
 			path = Views;
 			sourceTree = "<group>";
 		};
+		46E057A12175F2F1003FB809 /* Gradient */ = {
+			isa = PBXGroup;
+			children = (
+				46E057A22175F2F1003FB809 /* UIGradientFilter.swift */,
+				46E057A32175F2F1003FB809 /* UIGradient+Metadata.swift */,
+			);
+			path = Gradient;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXHeadersBuildPhase section */
@@ -152,7 +163,8 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 4639DD5421451CFA0038E5A6 /* Build configuration list for PBXNativeTarget "Randient" */;
 			buildPhases = (
-				46FB496A21453142005363F7 /* Load Latest Gradients */,
+				46E057A62175F5E3003FB809 /* SwiftLint */,
+				46FB496A21453142005363F7 /* Generate Gradients */,
 				4639DD4721451CFA0038E5A6 /* Sources */,
 				4639DD4821451CFA0038E5A6 /* Frameworks */,
 				4639DD4921451CFA0038E5A6 /* Headers */,
@@ -240,14 +252,32 @@
 /* End PBXResourcesBuildPhase section */
 
 /* Begin PBXShellScriptBuildPhase section */
-		46FB496A21453142005363F7 /* Load Latest Gradients */ = {
+		46E057A62175F5E3003FB809 /* SwiftLint */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+			);
+			inputPaths = (
+			);
+			name = SwiftLint;
+			outputFileListPaths = (
+			);
+			outputPaths = (
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "if which swiftlint >/dev/null; then\n    swiftlint\nfi\n";
+		};
+		46FB496A21453142005363F7 /* Generate Gradients */ = {
 			isa = PBXShellScriptBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
 			);
 			inputPaths = (
 			);
-			name = "Load Latest Gradients";
+			name = "Generate Gradients";
 			outputPaths = (
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -263,10 +293,11 @@
 			files = (
 				4622FF9D216755D400214563 /* UIGradient.swift in Sources */,
 				46DBB9DC215173E40094B965 /* UIColor+Interpolation.swift in Sources */,
-				46DBB9CE21516B290094B965 /* UIGradient+Metadata.swift in Sources */,
 				46DBB9D8215173D40094B965 /* UIColor+Analysis.swift in Sources */,
 				46DBB9DA215173D40094B965 /* GradientView.swift in Sources */,
+				46E057A52175F2F1003FB809 /* UIGradient+Metadata.swift in Sources */,
 				464BE4E321455020009B2A0D /* Randient.swift in Sources */,
+				46E057A42175F2F1003FB809 /* UIGradientFilter.swift in Sources */,
 				46DBB9D9215173D40094B965 /* RandientView.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;

Sources/Randient/Extensions/UIColor+Analysis.swift

@@ -18,4 +18,3 @@ internal extension UIColor {
         return brightness >= 0.5
     }
 }
-

Sources/Randient/Gradient/UIGradientFilter.swift

@@ -0,0 +1,35 @@
+//
+//  UIGradientFilter.swift
+//  Randient
+//
+//  Created by Merrick Sapsford on 16/10/2018.
+//  Copyright © 2018 UI At Six. All rights reserved.
+//
+
+import UIKit
+
+/// Filter that can be applied to a `UIGradient`.
+public final class UIGradientFilter {
+
+    // MARK: Types
+
+    public typealias Execution = (UIGradient) -> Bool
+
+    // MARK: Properties
+
+    internal let identifier = NSUUID().uuidString
+    internal let execution: Execution
+
+    // MARK: Init
+
+    internal init(execution: @escaping Execution) {
+        self.execution = execution
+    }
+}
+
+extension UIGradientFilter: Equatable {
+
+    public static func == (lhs: UIGradientFilter, rhs: UIGradientFilter) -> Bool {
+        return lhs.identifier == rhs.identifier
+    }
+}

Sources/Randient/Randient.swift

@@ -10,35 +10,91 @@ import Foundation
 
 public class Randient {
 
+    // MARK: Properties
+
+    /// Filters that are applied to random selection.
+    public private(set) static var filters = [UIGradientFilter]()
+
     /// The last randomized gradient.
     private static var lastGradient: UIGradient?
 
+    // MARK: Randomization
+
     /// Randomly select a new gradient from `UIGradients`.
     ///
     /// - Returns: Randomly selected gradient.
     public class func randomize() -> UIGradient {
         let allGradients = UIGradient.allCases
         let index = Int.random(in: 0 ..< allGradients.count)
 
-        if let newGradient = verifyNewGradient(allGradients[index]) {
+        if let newGradient = verifyGradient(allGradients[index]) {
             return newGradient
         } else {
             return randomize()
         }
     }
+}
+
+// MARK: - Verification
+extension Randient {
+
+    internal class func verifyGradient(_ gradient: UIGradient) -> UIGradient? {
+        guard let gradient = verifyIsNewGradient(gradient) else {
+            return nil
+        }
+        guard checkGradient(gradient, passes: Randient.filters) else {
+            return nil
+        }
+
+        return gradient
+    }
 
     /// Verify that the new gradient can be used.
     ///
     /// Checks that it is not equal to the previously returned gradient.
     ///
     /// - Parameter gradient: New gradient.
     /// - Returns: Gradient if it can be used.
-    internal class func verifyNewGradient(_ gradient: UIGradient) -> UIGradient? {
+    internal class func verifyIsNewGradient(_ gradient: UIGradient) -> UIGradient? {
         guard gradient.data.colors != lastGradient?.data.colors else {
             return nil
         }
+        guard checkGradient(gradient, passes: Randient.filters) else {
+            return nil
+        }
 
         self.lastGradient = gradient
         return gradient
     }
 }
+
+// MARK: - Filtering
+public extension Randient {
+
+    /// Add a new filter that is applied to the randomly selected gradients.
+    ///
+    /// - Parameter filters: Execution of the filter.
+    public class func addFilter(that filters: @escaping UIGradientFilter.Execution) {
+        Randient.filters.append(UIGradientFilter(execution: filters))
+    }
+
+    /// Remove a filter from being applied to random selection.
+    ///
+    /// - Parameter filter: Filter to remove.
+    public class func removeFilter(_ filter: UIGradientFilter) {
+        guard let index = Randient.filters.index(of: filter) else {
+            return
+        }
+        Randient.filters.remove(at: index)
+    }
+
+    internal class func checkGradient(_ gradient: UIGradient,
+                                      passes filters: [UIGradientFilter]) -> Bool {
+        for filter in filters {
+            if filter.execution(gradient) == false {
+                return false
+            }
+        }
+        return true
+    }
+}

Sources/Randient/Views/GradientView.swift

@@ -14,12 +14,10 @@ open class GradientView: UIView {
     // MARK: Properties
 
     private var gradientLayer: CAGradientLayer? {
-        get {
-            if let gradientLayer = self.layer as? CAGradientLayer {
-                return gradientLayer
-            }
-            return nil
+        if let gradientLayer = self.layer as? CAGradientLayer {
+            return gradientLayer
         }
+        return nil
     }
 
     /// The colors that are currently active in the gradient. Animatable.

Sources/RandientTests/RandientTests.swift

@@ -13,7 +13,7 @@ class RandientTests: XCTestCase {
 
     func testNewGradientVerification() {
         let gradient = Randient.randomize()
-        let verifiedGradient = Randient.verifyNewGradient(gradient)
+        let verifiedGradient = Randient.verifyIsNewGradient(gradient)
         XCTAssertNil(verifiedGradient)
     }
 }