Test 3D Touch peek/pop using private APIs

WFSimulate3DTouchPreview.m

@interface UIPreviewForceInteractionProgress : NSObject

- (void)endInteraction:(BOOL)arg1;

@end

@interface UIPreviewInteractionController : NSObject

@property (nonatomic, readonly) UIPreviewForceInteractionProgress *interactionProgressForPresentation;

- (BOOL)startInteractivePreviewAtPosition:(CGPoint)point inView:(UIView *)view;
- (void)cancelInteractivePreview;
- (void)commitInteractivePreview;

@end

@interface _UIViewControllerPreviewSourceViewRecord : NSObject <UIViewControllerPreviewing>

@property (nonatomic, readonly) UIPreviewInteractionController *previewInteractionController;

@end

void WFSimulate3DTouchPreview(id<UIViewControllerPreviewing> previewer, CGPoint sourceLocation) {
    _UIViewControllerPreviewSourceViewRecord *record = (_UIViewControllerPreviewSourceViewRecord *)previewer;
    UIPreviewInteractionController *interactionController = record.previewInteractionController;
    [interactionController startInteractivePreviewAtPosition:sourceLocation inView:record.sourceView];
    
    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
        [interactionController.interactionProgressForPresentation endInteraction:YES];
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            [interactionController commitInteractivePreview];
            //[interactionController cancelInteractivePreview];
        });
    });
}

/**
How to Use:

(in MyViewController.m:)
id<UIViewControllerPreviewing> previewer = [self registerForPreviewingWithDelegate:self sourceView:self.view];
UICollectionViewCell *cell = [self.collectionView cellForRowAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:0]];
WFSimulate3DTouchPreview(previewer, cell.frame.origin);

*/

Note: previewActionItems aren't displayed via this method. It's a bit tough to do so since they're normally brought on screen via a continuous gesture. Open to suggestions!

Just a heads up.

startInteractivePreviewAtPosition is now startInteractivePreviewAtLocation

Thanks for this!