Creating RiveFile is more Objective-C like

Example-iOS/Source/MyRiveViewController.swift

@@ -14,7 +14,8 @@ class MyRiveViewController: UIViewController {
     var resourceName: String?
     var resourceExt: String?
     var artboard: RiveArtboard?
-    var instance: RiveLinearAnimationInstance?
+    var instance0: RiveLinearAnimationInstance?
+    var instance1: RiveLinearAnimationInstance?
     var displayLink: CADisplayLink?
     var lastTime: CFTimeInterval = 0
     
@@ -53,7 +54,6 @@ class MyRiveViewController: UIViewController {
         }
         
         // Import the data into a RiveFile
-        let riveFile = RiveFile()
         let bytes = [UInt8](data)
         
         data.withUnsafeMutableBytes{(riveBytes:UnsafeMutableRawBufferPointer) in
@@ -61,12 +61,13 @@ class MyRiveViewController: UIViewController {
                 fatalError("File pointer is messed up")
             }
             let pointer = rawPointer.bindMemory(to: UInt8.self, capacity: bytes.count)
-            let importResult = RiveFile.import(pointer, bytesLength: UInt64(bytes.count), to: riveFile)
-
-            if (importResult != ImportResult.success) {
+            
+            guard let riveFile = RiveFile(bytes:pointer, byteLength: UInt64(bytes.count)) else {
                 fatalError("Failed to import \(url).")
             }
+            
             let artboard = riveFile.artboard()
+            
             self.artboard = artboard
             // update the artboard in the view
             (self.view as! MyRiveView).updateArtboard(artboard)
@@ -76,16 +77,23 @@ class MyRiveViewController: UIViewController {
             }
 
             // Fetch the animation and draw a first frame
-            let animation = artboard.animation(at: 0)
-            let instance = animation.instance()
-            self.instance = instance
-            instance.advance(by: 0)
-            instance.apply(to: artboard)
+//            let animation = artboard.animation(at: 0)
+//            self.instance = animation.instance()
+//            instance.advance(by: 0)
+//            instance.apply(to: artboard)
+//            artboard.advance(by: 0)
+                        
+            // Fetch two animations and advance the artboard
+            let animation0 = artboard.animation(at: 0)
+            self.instance0 = animation0.instance()
+            
+            let animation1 = artboard.animation(at: 1)
+            self.instance1 = animation1.instance()
+
             artboard.advance(by: 0)
             
             // Run the looping timer
             runTimer()
-            
         }
     }
     
@@ -118,8 +126,12 @@ class MyRiveViewController: UIViewController {
         lastTime = timestamp;
         
         // Advance the animation instance and the artboard
-        instance?.advance(by: elapsedTime) // advance the animation
-        instance?.apply(to: artboard)      // apply to the artboard
+        instance0!.advance(by: elapsedTime) // advance the animation
+        instance0!.apply(to: artboard)      // apply to the artboard
+        
+        instance1!.advance(by: elapsedTime)
+        instance1!.apply(to: artboard)
+        
         artboard.advance(by: elapsedTime) // advance the artboard
         
         // Trigger a redraw

Source/Rive.h

@@ -55,7 +55,7 @@ typedef NS_ENUM(NSInteger, ImportResult) {
 // Animation wrapper
 @interface RiveAnimation : NSObject
 
-- (NSString *) name;
+-(NSString *) name;
 -(RiveLinearAnimationInstance *) instance;
 
 @end
@@ -86,11 +86,10 @@ typedef NS_ENUM(NSInteger, ImportResult) {
 @property (class, readonly) uint majorVersion;
 @property (class, readonly) uint minorVersion;
 
-+ (ImportResult) import:(nonnull UInt8*)bytes bytesLength:(UInt64)length toFile:(nonnull RiveFile*)riveFile;
+-(nullable instancetype) initWithBytes:(UInt8 *)bytes byteLength:(UInt64)length;
 
 // Wraps: Artboard* artboard() const;
-- (RiveArtboard *) artboard;
-
+-(RiveArtboard *) artboard;
 @end
 
 NS_ASSUME_NONNULL_END

Source/Rive.mm

@@ -126,25 +126,26 @@
 
 // RIVE FILE
 
-@implementation RiveFile
-
-    rive::File *file;
+@implementation RiveFile {
+    rive::File* riveFile;
+}
 
 + (uint) majorVersion { return UInt8(rive::File::majorVersion); }
 + (uint) minorVersion { return UInt8(rive::File::minorVersion); }
 
-// Imports a Rive file, through a parameter reference
-+ (ImportResult) import:(nonnull UInt8 *)bytes bytesLength:(UInt64)length toFile:(nonnull RiveFile *)riveFile {
-    rive::BinaryReader reader = rive::BinaryReader(bytes, length);
-    rive::ImportResult result = rive::File::import(reader, &file);
-    if (result == rive::ImportResult::success) {
-        return success;
+-(nullable instancetype) initWithBytes:(UInt8 *)bytes byteLength:(UInt64)length {
+    if (self = [super init]) {
+        rive::BinaryReader reader = rive::BinaryReader(bytes, length);
+        rive::ImportResult result = rive::File::import(reader, &riveFile);
+        if (result == rive::ImportResult::success) {
+            return self;
+        }
     }
-    return malformed;
+    return nil;
 }
 
 - (RiveArtboard *) artboard {
-    return [[RiveArtboard alloc] initWithArtboard: file->artboard()];
+    return [[RiveArtboard alloc] initWithArtboard: riveFile->artboard()];
 }
 
 @end