Retain cropData object in ImageEditingManager.cropImage

Summary:
All struct args are passed into NativeModule methods via references. If blocks access those references, we don't move those references to the heap. This means that by the time that the block accesses the struct arg, it could be freed. This can crash the program.

The solution is simple: we copy the struct arg, and access the copy in the block. This ensures that the block will make a copy, which prevents the underlying data structures from being released by the time that the block accesses the struct arg.

Changelog:
[iOS][Fixed] - Retain cropData struct arg in ImageEditingManager.cropImage call

Differential Revision: D18076026

fbshipit-source-id: 1a7bb602606ff1afac38ad5451662c82fa86f205

Libraries/Image/RCTImageEditingManager.mm

@@ -53,6 +53,9 @@ @implementation RCTImageEditingManager
       @"height": @(cropData.size().height()),
     }]
   };
+
+  // We must keep a copy of cropData so that we can access data from it at a later time
+  JS::NativeImageEditor::Options cropDataCopy = cropData;
 
   [[_bridge moduleForName:@"ImageLoader" lazilyLoadIfNecessary:YES]
    loadImageWithURLRequest:imageRequest callback:^(NSError *error, UIImage *image) {
@@ -68,9 +71,9 @@ @implementation RCTImageEditingManager
      UIImage *croppedImage = RCTTransformImage(image, targetSize, image.scale, transform);
 
      // Scale image
-     if (cropData.displaySize()) {
-       targetSize = [RCTConvert CGSize:@{@"width": @(cropData.displaySize()->width()), @"height": @(cropData.displaySize()->height())}]; // in pixels
-       RCTResizeMode resizeMode = [RCTConvert RCTResizeMode:cropData.resizeMode() ?: @"contain"];
+     if (cropDataCopy.displaySize()) {
+       targetSize = [RCTConvert CGSize:@{@"width": @(cropDataCopy.displaySize()->width()), @"height": @(cropDataCopy.displaySize()->height())}]; // in pixels
+       RCTResizeMode resizeMode = [RCTConvert RCTResizeMode:cropDataCopy.resizeMode() ?: @"contain"];
        targetRect = RCTTargetRect(croppedImage.size, targetSize, 1, resizeMode);
        transform = RCTTransformFromTargetRect(croppedImage.size, targetRect);
        croppedImage = RCTTransformImage(croppedImage, targetSize, image.scale, transform);