Adding the view in a UIWindow before taking the snapshot

Author: Patrik Tomas Chamelo

FBSnapshotTestCase/Categories/UIImage+Snapshot.h

@@ -12,6 +12,13 @@
 
 @interface UIImage (Snapshot)
 
-+ (UIImage *)fb_imageForViewOrLayer:(id)viewOrLayer;
+/// Uses renderInContext: to get a snapshot of the layer.
++ (UIImage *)fb_imageForLayer:(CALayer *)layer;
+
+/// Uses renderInContext: to get a snapshot of the view layer.
++ (UIImage *)fb_imageForViewLayer:(UIView *)view;
+
+/// Uses drawViewHierarchyInRect: to get a snapshot of the view and adds the view into a window if needed.
++ (UIImage *)fb_imageForView:(UIView *)view;
 
 @end

FBSnapshotTestCase/Categories/UIImage+Snapshot.m

@@ -12,20 +12,6 @@
 
 @implementation UIImage (Snapshot)
 
-+ (UIImage *)fb_imageForViewOrLayer:(id)viewOrLayer
-{
-  if ([viewOrLayer isKindOfClass:[UIView class]]) {
-    return [self fb_imageForView:viewOrLayer];
-  } else if ([viewOrLayer isKindOfClass:[CALayer class]]) {
-    CALayer *layer = (CALayer *)viewOrLayer;
-    [layer layoutIfNeeded];
-    return [self fb_imageForLayer:layer];
-  } else {
-    [NSException raise:@"Only UIView and CALayer classes can be snapshotted" format:@"%@", viewOrLayer];
-  }
-  return nil;
-}
-
 + (UIImage *)fb_imageForLayer:(CALayer *)layer
 {
   CGRect bounds = layer.bounds;
@@ -35,8 +21,8 @@ + (UIImage *)fb_imageForLayer:(CALayer *)layer
   UIGraphicsBeginImageContextWithOptions(bounds.size, NO, 0);
   CGContextRef context = UIGraphicsGetCurrentContext();
   NSAssert1(context, @"Could not generate context for layer %@", layer);
-
   CGContextSaveGState(context);
+  [layer layoutIfNeeded];
   [layer renderInContext:context];
   CGContextRestoreGState(context);
 
@@ -45,10 +31,32 @@ + (UIImage *)fb_imageForLayer:(CALayer *)layer
   return snapshot;
 }
 
-+ (UIImage *)fb_imageForView:(UIView *)view
++ (UIImage *)fb_imageForViewLayer:(UIView *)view
 {
   [view layoutIfNeeded];
   return [self fb_imageForLayer:view.layer];
 }
 
++ (UIImage *)fb_imageForView:(UIView *)view
+{
+  CGRect bounds = view.bounds;
+  NSAssert1(CGRectGetWidth(bounds), @"Zero width for view %@", view);
+  NSAssert1(CGRectGetHeight(bounds), @"Zero height for view %@", view);  
+
+  UIWindow *window = view.window;
+  if (window == nil) {
+    window = [[UIWindow alloc] initWithFrame:bounds];
+    [window addSubview:view];
+    [window makeKeyAndVisible];
+  }
+  
+  UIGraphicsBeginImageContextWithOptions(bounds.size, NO, 0);
+  [view layoutIfNeeded];
+  [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
+
+  UIImage *snapshot = UIGraphicsGetImageFromCurrentImageContext();
+  UIGraphicsEndImageContext();
+  return snapshot;
+}
+
 @end

FBSnapshotTestCase/FBSnapshotTestCase.h

@@ -94,6 +94,17 @@ FBSnapshotVerifyLayerWithOptions(layer__, identifier__, FBSnapshotTestCaseDefaul
  */
 @property (readwrite, nonatomic, assign) BOOL recordMode;
 
+/**
+ When YES, renders a snapshot of the complete view hierarchy as visible onscreen.
+ There are several things that do not work if renderInContext: is used.
+ - UIVisualEffect #70
+ - UIApperance #91
+ - Size Classes #92
+ 
+ @attention If the view does't belong to a UIWindow, it will create one and add the view as a subview.
+ */
+@property (readwrite, nonatomic, assign) BOOL usesDrawViewHierarchyInRect;
+
 - (void)setUp NS_REQUIRES_SUPER;
 - (void)tearDown NS_REQUIRES_SUPER;
 

FBSnapshotTestCase/FBSnapshotTestCase.m

@@ -41,6 +41,17 @@ - (void)setRecordMode:(BOOL)recordMode
   _snapshotController.recordMode = recordMode;
 }
 
+- (BOOL)usesDrawViewHierarchyInRect
+{
+  return _snapshotController.usesDrawViewHierarchyInRect;
+}
+
+- (void)setUsesDrawViewHierarchyInRect:(BOOL)usesDrawViewHierarchyInRect
+{
+  NSAssert1(_snapshotController, @"%s cannot be called before [super setUp]", __FUNCTION__);
+  _snapshotController.usesDrawViewHierarchyInRect = usesDrawViewHierarchyInRect;
+}
+
 #pragma mark - Public API
 
 - (BOOL)compareSnapshotOfLayer:(CALayer *)layer

FBSnapshotTestCase/FBSnapshotTestController.h

@@ -37,9 +37,14 @@ extern NSString *const FBReferenceImageFilePathKey;
 
 /**
  Record snapshots.
- **/
+ */
 @property (readwrite, nonatomic, assign) BOOL recordMode;
 
+/**
+ Uses drawViewHierarchyInRect:afterScreenUpdates: to draw the image instead of renderInContext:
+ */
+@property (readwrite, nonatomic, assign) BOOL usesDrawViewHierarchyInRect;
+
 /**
  The directory in which referfence images are stored.
  */

FBSnapshotTestCase/FBSnapshotTestController.m

@@ -268,7 +268,7 @@ - (BOOL)_performPixelComparisonWithViewOrLayer:(id)viewOrLayer
 {
   UIImage *referenceImage = [self referenceImageForSelector:selector identifier:identifier error:errorPtr];
   if (nil != referenceImage) {
-    UIImage *snapshot = [UIImage fb_imageForViewOrLayer:viewOrLayer];
+    UIImage *snapshot = [self _imageForViewOrLayer:viewOrLayer];
     BOOL imagesSame = [self compareReferenceImage:referenceImage toImage:snapshot tolerance:tolerance error:errorPtr];
     if (!imagesSame) {
       [self saveFailedReferenceImage:referenceImage
@@ -287,7 +287,7 @@ - (BOOL)_recordSnapshotOfViewOrLayer:(id)viewOrLayer
                           identifier:(NSString *)identifier
                                error:(NSError **)errorPtr
 {
-  UIImage *snapshot = [UIImage fb_imageForViewOrLayer:viewOrLayer];
+  UIImage *snapshot = [self _imageForViewOrLayer:viewOrLayer];
   return [self _saveReferenceImage:snapshot selector:selector identifier:identifier error:errorPtr];
 }
 
@@ -329,4 +329,20 @@ - (BOOL)_saveReferenceImage:(UIImage *)image
   return didWrite;
 }
 
+- (UIImage *)_imageForViewOrLayer:(id)viewOrLayer
+{
+  if ([viewOrLayer isKindOfClass:[UIView class]]) {
+    if (_usesDrawViewHierarchyInRect) {
+      return [UIImage fb_imageForView:viewOrLayer];
+    } else {
+      return [UIImage fb_imageForViewLayer:viewOrLayer];
+    }
+  } else if ([viewOrLayer isKindOfClass:[CALayer class]]) {
+    return [UIImage fb_imageForLayer:viewOrLayer];
+  } else {
+    [NSException raise:@"Only UIView and CALayer classes can be snapshotted" format:@"%@", viewOrLayer];
+  }
+  return nil;
+}
+
 @end

FBSnapshotTestCaseDemo/FBSnapshotTestCaseDemo.xcodeproj/project.pbxproj

@@ -12,7 +12,6 @@
 		B30449221AB794320067C75D /* FBSnapshotTestCaseDemoTests.m in Sources */ = {isa = PBXBuildFile; fileRef = B30449211AB794320067C75D /* FBSnapshotTestCaseDemoTests.m */; };
 		B30449351AB795230067C75D /* InfoPlist.strings in Resources */ = {isa = PBXBuildFile; fileRef = B304492C1AB795230067C75D /* InfoPlist.strings */; };
 		B30449361AB795230067C75D /* FBAppDelegate.m in Sources */ = {isa = PBXBuildFile; fileRef = B304492F1AB795230067C75D /* FBAppDelegate.m */; };
-		B30449371AB795230067C75D /* FBExampleView.m in Sources */ = {isa = PBXBuildFile; fileRef = B30449311AB795230067C75D /* FBExampleView.m */; };
 		B30449381AB795230067C75D /* FBSnapshotTestCaseDemo-Info.plist in Resources */ = {isa = PBXBuildFile; fileRef = B30449321AB795230067C75D /* FBSnapshotTestCaseDemo-Info.plist */; };
 		B30449391AB795230067C75D /* Images.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = B30449341AB795230067C75D /* Images.xcassets */; };
 		F02D88451B1F246300BFBC1D /* FBSnapshotTestCaseSwiftTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F02D88441B1F246300BFBC1D /* FBSnapshotTestCaseSwiftTests.swift */; };
@@ -40,8 +39,6 @@
 		B304492D1AB795230067C75D /* en */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = en; path = InfoPlist.strings; sourceTree = "<group>"; };
 		B304492E1AB795230067C75D /* FBAppDelegate.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FBAppDelegate.h; sourceTree = "<group>"; };
 		B304492F1AB795230067C75D /* FBAppDelegate.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FBAppDelegate.m; sourceTree = "<group>"; };
-		B30449301AB795230067C75D /* FBExampleView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = FBExampleView.h; sourceTree = "<group>"; };
-		B30449311AB795230067C75D /* FBExampleView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = FBExampleView.m; sourceTree = "<group>"; };
 		B30449321AB795230067C75D /* FBSnapshotTestCaseDemo-Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = "FBSnapshotTestCaseDemo-Info.plist"; sourceTree = "<group>"; };
 		B30449331AB795230067C75D /* FBSnapshotTestCaseDemo-Prefix.pch */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "FBSnapshotTestCaseDemo-Prefix.pch"; sourceTree = "<group>"; };
 		B30449341AB795230067C75D /* Images.xcassets */ = {isa = PBXFileReference; lastKnownFileType = folder.assetcatalog; path = Images.xcassets; sourceTree = "<group>"; };
@@ -103,8 +100,6 @@
 				B304492B1AB795230067C75D /* en.lproj */,
 				B304492E1AB795230067C75D /* FBAppDelegate.h */,
 				B304492F1AB795230067C75D /* FBAppDelegate.m */,
-				B30449301AB795230067C75D /* FBExampleView.h */,
-				B30449311AB795230067C75D /* FBExampleView.m */,
 				B30449321AB795230067C75D /* FBSnapshotTestCaseDemo-Info.plist */,
 				B30449331AB795230067C75D /* FBSnapshotTestCaseDemo-Prefix.pch */,
 				B30449341AB795230067C75D /* Images.xcassets */,
@@ -307,7 +302,6 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
-				B30449371AB795230067C75D /* FBExampleView.m in Sources */,
 				B30449361AB795230067C75D /* FBAppDelegate.m in Sources */,
 				B30449081AB794320067C75D /* main.m in Sources */,
 			);

FBSnapshotTestCaseDemo/FBSnapshotTestCaseDemo/FBExampleView.h

@@ -14,6 +14,11 @@
       "idiom" : "iphone",
       "size" : "60x60",
       "scale" : "2x"
+    },
+    {
+      "idiom" : "iphone",
+      "size" : "60x60",
+      "scale" : "3x"
     }
   ],
   "info" : {