最近开发的一个项目中，UIImagePickerController拍照后黑屏，点击确认后也可以显示照片，而且每次黑屏出现的时候会有CGAffineTransformInvert: singular matrix错误信息。最初一直再上述错误中徘徊，找解决方案。查询多次，stackoverflow上各种可能的方法都试了，依然无果。百思不得其解！到底哪里出现了问题呢？
无奈，静下来，想，首先我要找到问题必然出现的原因，于是，经过反复测试，终于到到出现的点。项目中引入了一个三房库弹框JCAlterView,每次触发弹框后，在去拍照的地方必然出现预览黑屏的问题。试着把弹框改成自定义的之后，问题解决了！！本来开始想去修改JCAlterView底层。发现底层操作UIApplication的rootViewController了。无奈，最后直接自定义样式换了JCAlterView,问题解决了。
唯一遗憾的是，由于时间问题，我没有追究为何改变UIApplication的rootVIewController后再次拍照会出现黑屏错误。
附上stackoverflow的各种解决方法。
【链接】yourcommunities
http://stackoverflow.com/questions/25884801/ios-8-snapshotting-a-view-that-has-not-been-rendered-results-in-an-empty-snapsho
http://stackoverflow.com/questions/21538781/uiimagepickercontroller-camera-blank-snapshot-image
down vote
I found the solution to my problem thanks to DevC's comment pointing me in the right direction. I used an ActionSheet to present the UIImagePickerController, so when clicking a button on it the animation still runs while the picker is opened. I solved it by closing the picker before I run the code that triggers thepicker:
- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
[actionSheet dismissWithClickedButtonIndex:999 animated:NO]; //non-existing button index so it doesn't trigger anything again
// Rest of code here (UIImagePickerController trigger)
}
