fix #23

Author: zoonooz

Classes/ZFRippleButton.swift

@@ -81,9 +81,9 @@ open class ZFRippleButton: UIButton {
 
         rippleBackgroundView.backgroundColor = rippleBackgroundColor
         rippleBackgroundView.frame = bounds
-        layer.addSublayer(rippleBackgroundView.layer)
-        rippleBackgroundView.layer.addSublayer(rippleView.layer)
+        rippleBackgroundView.addSubview(rippleView)
         rippleBackgroundView.alpha = 0
+        addSubview(rippleBackgroundView)
 
         layer.shadowRadius = 0
         layer.shadowOffset = CGSize(width: 0, height: 1)

Demo/ZFRippleButtonDemo/ZFRippleButtonDemo.xcodeproj/project.pbxproj

@@ -353,7 +353,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				INFOPLIST_FILE = ZFRippleButtonDemo/Info.plist;
-				IPHONEOS_DEPLOYMENT_TARGET = 7.1;
+				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_VERSION = 3.0;
@@ -365,7 +365,7 @@
 			buildSettings = {
 				ASSETCATALOG_COMPILER_APPICON_NAME = AppIcon;
 				INFOPLIST_FILE = ZFRippleButtonDemo/Info.plist;
-				IPHONEOS_DEPLOYMENT_TARGET = 7.1;
+				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
 				LD_RUNPATH_SEARCH_PATHS = "$(inherited) @executable_path/Frameworks";
 				PRODUCT_NAME = "$(TARGET_NAME)";
 				SWIFT_VERSION = 3.0;