Covert UIVIew to UIImage without presenting/displaying UIView - ios

Question

I am using method to convert UIView to UIImage and its doing a great job when UIView (to be converted to UIImage) is already present/displayed. But my requirement is to convert UIView to UIImage without displaying UIView. Unfortunately, this code is failing in this case and I am stuck. Any help will be appreciated.
I am using the following method:
+ (UIImage *) imageWithView:(UIView *)view
{
UIGraphicsBeginImageContextWithOptions(view.bounds.size, view.opaque, [[UIScreen mainScreen] scale]);
[view.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage * img = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return img;
}

Answer 1

Your code is likely failing because you're not laying out the subviews of your view (which is done automatically when you add a view as a subview). Try something like the method I wrote below:
+ (UIImage *)imageFromView:(UIView *)view sized:(CGSize)size
{
// layout the view
view.frame = CGRectMake(0, 0, size.width, size.height);
[view setNeedsLayout];
[view layoutIfNeeded];
// render the image
UIGraphicsBeginImageContextWithOptions(size, view.opaque, 0.0f);
[view drawViewHierarchyInRect:view.bounds afterScreenUpdates:NO];
UIImage *renderedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return renderedImage;
}

Answer 2

Assuming you have already got a working view, this code should work to convert the UIView to a UIImage (I'm using it to convert a gradient into an image and display the image onto a UIProgressView.
Swift:
let renderer = UIGraphicsImageRenderer(size: gradientView.bounds.size)
let image = renderer.image { ctx in
gradientView.drawHierarchy(in: gradientView.bounds, afterScreenUpdates: true)
}
Objective C:
UIGraphicsImageRenderer *renderer = [[UIGraphicsImageRenderer alloc] initWithSize:gradientView.bounds.size];
UIImage *gradientImage = [renderer imageWithActions:^(UIGraphicsImageRendererContext * _Nonnull rendererContext) {
[gradientView drawViewHierarchyInRect:gradientView.bounds afterScreenUpdates:true];
}];
_progressView.progressImage = gradientImage;
The above code should allow you to convert any UIView to a UIImage. You should ideally be running it in the viewWillAppear (as at this point the view controller will have the correct layout sizes). If you have any problems getting this to work you can have a look at these example projects that I made for a guide on this very topic! Objective C, Swift.

Answer 3

Hide all subviews, and then snapshot UIview to UIImage should work, see code below
+ (UIImage *)custom_snapshotScreenInView:(UIView *)contentView
{
if (!contentView) {
return nil;
}
CGSize size = contentView.bounds.size;
UIGraphicsBeginImageContextWithOptions(size, NO, [UIScreen mainScreen].scale);
CGRect rect = contentView.bounds;
[contentView drawViewHierarchyInRect:rect afterScreenUpdates:YES];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
return image;
}
+ (UIImage *)custom_snapshotScreenWithoutSubviews:(UIView *)contentView
{
// save hidden view's hash
NSMutableArray *hideViewsHashs = [[NSMutableArray alloc]initWithCapacity:contentView.subviews.count];
for (UIView *subview in contentView.subviews) {
if (subview.hidden == NO) {
[hideViewsHashs addObject:#(subview.hash)];
NSLog(#"Dikey:video:snap:hash = %#", #(subview.hash));
}
subview.hidden = YES;
}
// view to image
UIImage *image = [UIImage custom_snapshotScreenInView:contentView];
// restore
for (UIView *subview in contentView.subviews) {
if ([hideViewsHashs containsObject:#(subview.hash)]) {
subview.hidden = NO;
NSLog(#"Dikey:video:snap:restore:hash = %#", #(subview.hash));
}
}
// finish
return image;
}