UIImagePickerCountroller设置导航栏左右按

• UIImagePickerCountroller继承自UINavigationController，要想修改backBarButtonIten和rightBarButtonItem的字体颜色，只需设置navigationBar.tintColor就可以

UIImagePickerController *picker = [[UIImagePickerController alloc] init];
picker.navigationBar.tintColor = [UIColor whiteColor];