微信小程序在真机IOS系统下面，选择时间的确定按钮没有出现

<uni-datetime-picker type="datetime" v-model="appointmentTime" @change="changeLog"  
        @show="showDatetime" @maskClick="tapMask">  
    <u-field v-model="appointmentTime" label="预约时间" input-align="right" placeholder="请选择预约时间"  
    required disabled></u-field>  
</uni-datetime-picker>