bug fix： http://jira.yoho.cn:8888/browse/YH-2658 review by 阿瑟

@@ -107,18 +107,17 @@ class UserNavBar extends React.Component {
     }
 
     componentWillUnmount() {
-
+        this.props.scrollValue.removeListener(this._listener);
     }
 
     setAnimationValue({ value, }) {
-        if (value <= 2) {
+        if (value >= 0 && value <= 2) {
             this.headerView.setNativeProps({
                 style: {
                     backgroundColor: this.headerColor(value),
                 },
             });
 
-            value = value + 0.1;
             value = value > 1 ? 1 : value;
             this.image.setNativeProps({
                 style: {