Quick fix for the iOS 11 problem

Author: Raul Riera

TextFieldEffects/TextFieldEffects/TextFieldEffects.swift

@@ -77,7 +77,13 @@ open class TextFieldEffects : UITextField {
  // MARK: - Overrides
 
  override open func draw(_ rect: CGRect) {
- drawViewsForRect(rect)
+// FIXME: Short-circuit if the view is currently selected. iOS 11 introduced
+// a setNeedsDisplay when you focus on a textfield, calling this method again
+// and messing up some of the effects due to the logic contained inside these
+// methods.
+// This is just a "quick fix", something better needs to come along.
+guard isFirstResponder == false else { return }
+drawViewsForRect(rect)
  }
 
  override open func drawPlaceholder(in rect: CGRect) {