Avoid crash caused by deallocing parent during scroll

Closes #68

Author: michaeltyson

TPKeyboardAvoiding/TPKeyboardAvoidingCollectionView.m

@@ -67,6 +67,13 @@ - (void)scrollToActiveTextField {
 
 #pragma mark - Responders, events
 
+-(void)willMoveToSuperview:(UIView *)newSuperview {
+    [super willMoveToSuperview:newSuperview];
+    if ( !newSuperview ) {
+        [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(TPKeyboardAvoiding_assignTextDelegateForViewsBeneathView:) object:self];
+    }
+}
+
 - (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
     [[self TPKeyboardAvoiding_findFirstResponderBeneathView:self] resignFirstResponder];
     [super touchesEnded:touches withEvent:event];

TPKeyboardAvoiding/TPKeyboardAvoidingScrollView.m

@@ -60,6 +60,13 @@ - (void)scrollToActiveTextField {
 
 #pragma mark - Responders, events
 
+-(void)willMoveToSuperview:(UIView *)newSuperview {
+    [super willMoveToSuperview:newSuperview];
+    if ( !newSuperview ) {
+        [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(TPKeyboardAvoiding_assignTextDelegateForViewsBeneathView:) object:self];
+    }
+}
+
 - (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
     [[self TPKeyboardAvoiding_findFirstResponderBeneathView:self] resignFirstResponder];
     [super touchesEnded:touches withEvent:event];

TPKeyboardAvoiding/TPKeyboardAvoidingTableView.m

@@ -62,6 +62,13 @@ - (void)scrollToActiveTextField {
 
 #pragma mark - Responders, events
 
+-(void)willMoveToSuperview:(UIView *)newSuperview {
+    [super willMoveToSuperview:newSuperview];
+    if ( !newSuperview ) {
+        [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(TPKeyboardAvoiding_assignTextDelegateForViewsBeneathView:) object:self];
+    }
+}
+
 - (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
     [[self TPKeyboardAvoiding_findFirstResponderBeneathView:self] resignFirstResponder];
     [super touchesEnded:touches withEvent:event];