因为我这也报了这个警告，所以把解决方法写到这个地方看是否其他人用的到，具体解决方法：
错误代码：Snapshotting a view that has not been rendered results in an empty snapshot. Ensure your view has been rendered at least once before snapshotting or snapshot after screen updates.
问题分析：iOS8在调用系统相机拍照时，会有
