Adds example using the combiner protocol. Closes #1.

Author: chriscox

README.md

@@ -53,3 +53,32 @@ myScrollView.delegate = _multiplexer;
 [_multiplexer addObservingDelegate:myControl];
 [_multiplexer addObservingDelegate:anotherControl];
 ```
+
+## Using the `GOSScrollViewDelegateCombining` protocol
+
+First conform to the `GOSScrollViewDelegateCombining` protocol:
+
+```objectivec
+@interface MyViewController () <GOSScrollViewDelegateCombining>
+@end
+
+[_multiplexer setCombiner:self];
+```
+
+Handle one of the `UIScrollViewDelegate` protocol methods that return a value:
+
+```objectivec
+- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
+  return myZoomingView;
+}
+```
+
+And finally return the desired observer's results from the combiner method:
+
+```objectivec
+- (UIView *)scrollViewDelegateMultiplexer:(GOSScrollViewDelegateMultiplexer *)multiplexer
+                viewForZoomingWithResults:(NSPointerArray *)results
+                  fromRespondingObservers:(NSArray *)respondingObservers {
+  return [results pointerAtIndex:0];
+}
+```

examples/SVDMTypicalUseViewController.m

@@ -26,11 +26,13 @@
 #define RGBCOLOR(r, g, b) [UIColor colorWithRed:(r) / 255.0f green:(g) / 255.0f blue:(b) / 255.0f alpha:1]
 #define HEXCOLOR(hex) RGBCOLOR((((hex) >> 16) & 0xFF), (((hex) >> 8) & 0xFF), ((hex)&0xFF))
 
+@interface SVDMTypicalUseViewController () <GOSScrollViewDelegateCombining>
+@end
+
 @implementation SVDMTypicalUseViewController {
   UIScrollView *_scrollView;
   UIPageControl *_pageControl;
   NSArray *_pageColors;
-
   GOSScrollViewDelegateMultiplexer *_multiplexer;
 }
 
@@ -52,18 +54,22 @@ - (void)viewDidLoad {
   _scrollView.pagingEnabled = YES;
   _scrollView.contentSize = CGSizeMake(boundsWidth * _pageColors.count, boundsHeight);
   _scrollView.minimumZoomScale = 0.5;
-  _scrollView.maximumZoomScale = 6.0;
+  _scrollView.maximumZoomScale = 1.5;
 
   // Add pages to scrollView.
   for (NSInteger i = 0; i < _pageColors.count; i++) {
     CGRect pageFrame = CGRectOffset(self.view.bounds, i * boundsWidth, 0);
-    UILabel *page = [[UILabel alloc] initWithFrame:pageFrame];
-    page.text = [NSString stringWithFormat:@"Page %zd", i + 1];
-    page.font = [UIFont systemFontOfSize:50];
-    page.textColor = [UIColor colorWithWhite:0 alpha:0.8];
-    page.textAlignment = NSTextAlignmentCenter;
+    UIView *page = [[UIView alloc] initWithFrame:pageFrame];
     page.backgroundColor = _pageColors[i];
     [_scrollView addSubview:page];
+
+    UILabel *pageTitle = [[UILabel alloc] initWithFrame:page.bounds];
+    pageTitle.text = [NSString stringWithFormat:@"Page %zd", i + 1];
+    pageTitle.font = [UIFont systemFontOfSize:50];
+    pageTitle.textColor = [UIColor colorWithWhite:0 alpha:0.8];
+    pageTitle.textAlignment = NSTextAlignmentCenter;
+    pageTitle.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight;
+    [page addSubview:pageTitle];
   }
 
   // Page control configuration
@@ -101,6 +107,19 @@ - (void)viewDidLoad {
   _scrollView.delegate = _multiplexer;
   [_multiplexer addObservingDelegate:self];
   [_multiplexer addObservingDelegate:pageControl];
+  [_multiplexer setCombiner:self];
+}
+
+#pragma mark - GOSScrollViewDelegateCombining
+
+- (UIView *)scrollViewDelegateMultiplexer:(GOSScrollViewDelegateMultiplexer *)multiplexer
+                viewForZoomingWithResults:(NSPointerArray *)results
+                  fromRespondingObservers:(NSArray *)respondingObservers {
+  // Lets return the results from the oberserver which is equal to self.
+  if (respondingObservers[0] == self) {
+    return [results pointerAtIndex:0];
+  }
+  return nil;
 }
 
 #pragma mark - UIScrollViewDelegate
@@ -111,6 +130,12 @@ - (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
   [_pageControl updateCurrentPageDisplay];
 }
 
+- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
+  // Since there are multiple observers, we will allow the combiner to return this page
+  // as the zooming view.
+  return scrollView.subviews[_pageControl.currentPage];
+}
+
 #pragma mark - User events
 
 - (void)didChangePage:(UIPageControl *)sender {