iOS 11 layout bug workaround. See slackhq slackhq#604.

Author: paulcarpenter

Source/SLKTextInputbar.m

@@ -117,6 +117,16 @@ - (void)layoutIfNeeded
     [super layoutIfNeeded];
 }
 
+// Compensate for layout bug in iOS 11 Beta 2
+- (void)layoutSubviews
+{
+    [super layoutSubviews];
+    
+    [self bringSubviewToFront:self.textView];
+    [self bringSubviewToFront:self.rightButton];
+    [self bringSubviewToFront:self.leftButton];
+}
+
 - (CGSize)intrinsicContentSize
 {
     return CGSizeMake(UIViewNoIntrinsicMetric, [self minimumInputbarHeight]);