react native Scrollview在某些时候滚动无效

                                                                react native Scrollview在某些时候滚动无效

今天在使用Scrollview的时候滚动没有效果，直接上代码：

   return(
<View style={{flex:1}}>
        <NavigatorHeader nav={this.props.nav} title="首页">NavigatorHeader>
        <HomeCategory nav={this.props.nav} ClickCallback={this.props.ClickCallback}>HomeCategory>
     <ScrollView showsVerticalScrollIndicator={false}>
       <HomeSwiper nav={this.props.nav}/>
       <HomePictureTitleText textTittle1={'卫视热播'} navigatior={this.props.nav} parentCode={'0909112305914'}/>
       <HomePictureTitleText textTittle1={'热门精选'} navigatior={this.props.nav} parentCode={'0909112423500'}/>
       <HomePictureTitleText textTittle1={'猜你喜欢'} navigatior={this.props.nav} parentCode={'0909112654380'}/>
       <HomePictureTitleText textTittle1={'为我推荐'} navigatior={this.props.nav} parentCode={'0909112712867'}/>
       
   ScrollView>
View>
   );

怎么样都不能滚动。

后在scrollview中最后加入一个空的布局就能滚动了：

在此做个记录：

   return(
<View style={{flex:1}}>
        <NavigatorHeader nav={this.props.nav} title="首页">NavigatorHeader>
        <HomeCategory nav={this.props.nav} ClickCallback={this.props.ClickCallback}>HomeCategory>
     <ScrollView showsVerticalScrollIndicator={false}>
       <HomeSwiper nav={this.props.nav}/>
       <HomePictureTitleText textTittle1={'卫视热播'} navigatior={this.props.nav} parentCode={'0909112305914'}/>
       <HomePictureTitleText textTittle1={'热门精选'} navigatior={this.props.nav} parentCode={'0909112423500'}/>
       <HomePictureTitleText textTittle1={'猜你喜欢'} navigatior={this.props.nav} parentCode={'0909112654380'}/>
       <HomePictureTitleText textTittle1={'为我推荐'} navigatior={this.props.nav} parentCode={'0909112712867'}/>
         <View style={{height:Platform.OS == 'ios' ? 0:30,}}>View>
   ScrollView>
View>
   );

做个问题具体的原因我现在也不清楚，有知道的麻烦告知一下。谢谢