修复iOS15以下的设备mp4播放闪退的问题

DevelopmentPods/FUSBDAlphaPlayer/FUSBDAlphaPlayer/Classes/BDAlphaPlayerMetalView.m

@@ -204,7 +204,11 @@
         self.mtkView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
         self.mtkView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
         self.mtkView.backgroundColor = UIColor.clearColor;
         self.mtkView.backgroundColor = UIColor.clearColor;
         self.mtkView.device = MTLCreateSystemDefaultDevice();
         self.mtkView.device = MTLCreateSystemDefaultDevice();
+        if (@available(iOS 15.0, *)) {
             self.mtkView.colorPixelFormat = MTLPixelFormatRGBA8Unorm;
             self.mtkView.colorPixelFormat = MTLPixelFormatRGBA8Unorm;
+        } else {
+            self.mtkView.colorPixelFormat = MTLPixelFormatBGRA8Unorm;
+        }
         [self addSubview:self.mtkView];
         [self addSubview:self.mtkView];
         
         
         self.metalRenderer = [[BDAlphaPlayerMetalRenderer alloc] initWithMetalKitView:self.mtkView];
         self.metalRenderer = [[BDAlphaPlayerMetalRenderer alloc] initWithMetalKitView:self.mtkView];