Merge pull request #15 from UrbanCompass/master

nil out tableView delegate on dealloc

DemoApp/ViewController.m

@@ -14,6 +14,22 @@ @interface ViewController ()
 
 @implementation ViewController
 
+- (void)dealloc
+{
+    // If tableView is scrolling as this VC is being dealloc'd
+    // it continues to send messages (scrollViewDidScroll:) to its delegate.
+    // This is fine if the delegate will outlive tableView (e.g. this VC would.)
+    // However, if the delegate is an instance that may be dealloc'd
+    // before the tableView
+    // (i.e. _scrollProxy may be dealloc'd prior to tableView being dealloc'd)
+    // the tableView will send messages to its delegate,
+    // which is defined with an "assign" (i.e. unsafe_unretained) property.
+    // This is a msgSend to non-nil'ed, invalid memory leading to a crash.
+    // If or when UIScrollView's delegate is referred to with "weak" rather
+    // than "assign", this can and should be removed.
+    self.tableView.delegate = nil;
+}
+
 - (void)viewDidLoad
 {
     [super viewDidLoad];