Changed vertical anchor to be optionally configurable.

Adds a new enum to control whether the empty view is pinned to the center, top, or bottom of its container. The vertical offset, if provided, will affect the offset of the provided anchor location (Top constant, if pinned to top. Center constant, if pinned to centerY, bottom constant, if pinned to bottom). This allows a bit more flexibility in how a client chooses to lay out the empty view to meet their unique requirements.

Source/UIScrollView+EmptyDataSet.h

@@ -10,6 +10,13 @@
 
 #import <UIKit/UIKit.h>
 
+typedef NS_ENUM (NSUInteger, DZNEmptyDataSetVerticalAnchorLocation) {
+    DZNEmptyDataSetVerticalAnchorLocationCenter = 0,
+    DZNEmptyDataSetVerticalAnchorLocationTop,
+    DZNEmptyDataSetVerticalAnchorLocationBottom
+};
+
+
 @protocol DZNEmptyDataSetSource;
 @protocol DZNEmptyDataSetDelegate;
 
@@ -86,7 +93,7 @@
  *
  *  @return image animation
  */
-- (CAAnimation *) imageAnimationForEmptyDataSet:(UIScrollView *) scrollView;
+- (CAAnimation *)imageAnimationForEmptyDataSet:(UIScrollView *) scrollView;
 
 /**
  Asks the data source for the title to be used for the specified button state.
@@ -153,6 +160,8 @@
  */
 - (CGFloat)spaceHeightForEmptyDataSet:(UIScrollView *)scrollView;
 
+- (DZNEmptyDataSetVerticalAnchorLocation)verticalAnchorLocationForEmptyDataSet:(UIScrollView *)scrollView;
+
 @end
 
 

Source/UIScrollView+EmptyDataSet.m

@@ -37,6 +37,7 @@ @interface DZNEmptyDataSetView : UIView
 
 @property (nonatomic, assign) CGFloat verticalOffset;
 @property (nonatomic, assign) CGFloat verticalSpace;
+@property (nonatomic, assign) DZNEmptyDataSetVerticalAnchorLocation verticalAnchorLocation;
 
 @property (nonatomic, assign) BOOL fadeInOnDisplay;
 
@@ -283,6 +284,15 @@ - (CGFloat)dzn_verticalSpace
     return 0.0;
 }
 
+- (DZNEmptyDataSetVerticalAnchorLocation)dzn_verticalAnchorLocation
+{
+    if (self.emptyDataSetSource && [self.emptyDataSetSource respondsToSelector:@selector(verticalAnchorLocationForEmptyDataSet:)]) {
+        return [self.emptyDataSetSource verticalAnchorLocationForEmptyDataSet:self];
+    }
+
+    return DZNEmptyDataSetVerticalAnchorLocationCenter;
+}
+
 
 #pragma mark - Delegate Getters & Events (Private)
 
@@ -519,6 +529,9 @@ - (void)dzn_reloadEmptyDataSet
         // Configure offset
         view.verticalOffset = [self dzn_verticalOffset];
 
+        // Configure anchor location
+        view.verticalAnchorLocation = [self dzn_verticalAnchorLocation];
+
         // Configure the empty dataset view
         view.backgroundColor = [self dzn_dataSetBackgroundColor];
         view.hidden = NO;
@@ -923,17 +936,33 @@ - (void)prepareForReuse
 - (void)setupConstraints
 {
     // First, configure the content view constaints
-    // The content view must alway be centered to its superview
+    // The content view must always be centered to its superview
     NSLayoutConstraint *centerXConstraint = [self equallyRelatedConstraintWithView:self.contentView attribute:NSLayoutAttributeCenterX];
-    NSLayoutConstraint *centerYConstraint = [self equallyRelatedConstraintWithView:self.contentView attribute:NSLayoutAttributeCenterY];
+    NSLayoutConstraint *verticalAnchorConstraint = nil;
+
+    switch (self.verticalAnchorLocation) {
+        case DZNEmptyDataSetVerticalAnchorLocationCenter: {
+            verticalAnchorConstraint = [self equallyRelatedConstraintWithView:self.contentView attribute:NSLayoutAttributeCenterY];
+            break;
+        }
+        case DZNEmptyDataSetVerticalAnchorLocationTop: {
+            verticalAnchorConstraint = [self equallyRelatedConstraintWithView:self.contentView attribute:NSLayoutAttributeTop];
+            break;
+        }
+        case DZNEmptyDataSetVerticalAnchorLocationBottom: {
+            verticalAnchorConstraint = [self equallyRelatedConstraintWithView:self.contentView attribute:NSLayoutAttributeBottom];
+            break;
+        }
+    }
+
 
     [self addConstraint:centerXConstraint];
-    [self addConstraint:centerYConstraint];
+    [self addConstraint:verticalAnchorConstraint];
     [self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[contentView]|" options:0 metrics:nil views:@{@"contentView": self.contentView}]];
 
     // When a custom offset is available, we adjust the vertical constraints' constants
     if (self.verticalOffset != 0 && self.constraints.count > 0) {
-        centerYConstraint.constant = self.verticalOffset;
+        verticalAnchorConstraint.constant = self.verticalOffset;
     }
 
     // If applicable, set the custom view's constraints