1.File's owner 不需要关联，只需关联根view的class
2.如果还是crash，则右击检查File's owner是否还有子view关联着它
PS:初始化方法示例：
+ (instancetype)initFromNib
{
NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"IDScreenShotView" owner:nil options:nil];
IDScreenShotView *shotView = [nib objectAtIndex:0];
return shotView;
}