diff --git a/ObjcQrExample/ViewController.m b/ObjcQrExample/ViewController.m
index 22411d4..97ced7b 100644
--- a/ObjcQrExample/ViewController.m
+++ b/ObjcQrExample/ViewController.m
@@ -19,9 +19,9 @@ @interface ViewController () <AVCaptureMetadataOutputObjectsDelegate>
 
 @implementation ViewController
 
-- (void)viewDidLoad {
-    [super viewDidLoad];
-    
+- (void)viewDidLayoutSubviews {
+    [super viewDidLayoutSubviews];
+
     CGRect previewRect = [self makePreviewRectWithFrame:self.view.frame];
     self.maskLayerView.layer.mask = [self makeMaskWithRect:previewRect inFrame:self.maskLayerView.frame];