Handle Camera Privacy Settings Failue

Show user alert view when camera access fails and if supported
allow user to directly launch settings app

Author: kharrison

QReader/QReader.xcodeproj/project.pbxproj

@@ -8,6 +8,7 @@
 
 /* Begin PBXBuildFile section */
 		5309FFAE19183E2800ADB15A /* UYLTextCell.m in Sources */ = {isa = PBXBuildFile; fileRef = 5309FFAD19183E2800ADB15A /* UYLTextCell.m */; };
+		53249C0419AF6D8400EA1639 /* Localizable.strings in Resources */ = {isa = PBXBuildFile; fileRef = 53249C0219AF6D8400EA1639 /* Localizable.strings */; };
 		532884FD19197D6C00E44C28 /* UYLCaptureViewController.m in Sources */ = {isa = PBXBuildFile; fileRef = 532884FC19197D6C00E44C28 /* UYLCaptureViewController.m */; };
 		5344A59918DF769400C61776 /* Foundation.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 5344A59818DF769400C61776 /* Foundation.framework */; };
 		5344A59B18DF769400C61776 /* CoreGraphics.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 5344A59A18DF769400C61776 /* CoreGraphics.framework */; };
@@ -26,6 +27,7 @@
 		5309FFAC19183E2800ADB15A /* UYLTextCell.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = UYLTextCell.h; sourceTree = "<group>"; };
 		5309FFAD19183E2800ADB15A /* UYLTextCell.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = UYLTextCell.m; sourceTree = "<group>"; };
 		53191C0C1922A774000DCCBB /* README */ = {isa = PBXFileReference; lastKnownFileType = text; path = README; sourceTree = "<group>"; };
+		53249C0319AF6D8400EA1639 /* en */ = {isa = PBXFileReference; lastKnownFileType = text.plist.strings; name = en; path = en.lproj/Localizable.strings; sourceTree = "<group>"; };
 		532884FB19197D6C00E44C28 /* UYLCaptureViewController.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = UYLCaptureViewController.h; sourceTree = "<group>"; };
 		532884FC19197D6C00E44C28 /* UYLCaptureViewController.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = UYLCaptureViewController.m; sourceTree = "<group>"; };
 		5344A59518DF769400C61776 /* QReader.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = QReader.app; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -135,6 +137,7 @@
 				5344A5A118DF769400C61776 /* InfoPlist.strings */,
 				5344A5A418DF769400C61776 /* main.m */,
 				5344A5A618DF769400C61776 /* QReader-Prefix.pch */,
+				53249C0219AF6D8400EA1639 /* Localizable.strings */,
 			);
 			name = "Supporting Files";
 			sourceTree = "<group>";
@@ -197,6 +200,7 @@
 			isa = PBXResourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				53249C0419AF6D8400EA1639 /* Localizable.strings in Resources */,
 				5344A5AF18DF769400C61776 /* Main_iPad.storyboard in Resources */,
 				5344A5B418DF769400C61776 /* Images.xcassets in Resources */,
 				5344A5AC18DF769400C61776 /* Main_iPhone.storyboard in Resources */,
@@ -223,6 +227,14 @@
 /* End PBXSourcesBuildPhase section */
 
 /* Begin PBXVariantGroup section */
+		53249C0219AF6D8400EA1639 /* Localizable.strings */ = {
+			isa = PBXVariantGroup;
+			children = (
+				53249C0319AF6D8400EA1639 /* en */,
+			);
+			name = Localizable.strings;
+			sourceTree = "<group>";
+		};
 		5344A5A118DF769400C61776 /* InfoPlist.strings */ = {
 			isa = PBXVariantGroup;
 			children = (

QReader/QReader/QReader-Info.plist

@@ -24,6 +24,8 @@
 	<string>1.0</string>
 	<key>LSRequiresIPhoneOS</key>
 	<true/>
+	<key>NSCameraUsageDescription</key>
+	<string>The camera is used to capture QR codes.</string>
 	<key>UIMainStoryboardFile</key>
 	<string>Main_iPhone</string>
 	<key>UIMainStoryboardFile~ipad</key>

QReader/QReader/UYLCaptureViewController.m

@@ -35,7 +35,7 @@
 #import "UYLCaptureViewController.h"
 #import "UYLTableViewController.h"
 
-@interface UYLCaptureViewController () <AVCaptureMetadataOutputObjectsDelegate>
+@interface UYLCaptureViewController () <AVCaptureMetadataOutputObjectsDelegate, UIAlertViewDelegate>
 
 @property (nonatomic, strong) AVCaptureVideoPreviewLayer *previewLayer;
 @property (nonatomic, strong) CALayer *targetLayer;
@@ -111,6 +111,7 @@ - (AVCaptureSession *)captureSession
         else
         {
             NSLog(@"Input Device error: %@",[error localizedDescription]);
+            [self showAlertForCameraError:error];
         }
     }
     return _captureSession;
@@ -197,10 +198,44 @@ - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:
     [self showDetectedObjects];
 }
 
+#pragma mark -
+#pragma mark === UIAlertViewDelegate ===
+#pragma mark -
+
+- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
+{
+    if (buttonIndex == 1)
+    {
+        NSURL *url = [NSURL URLWithString:UIApplicationOpenSettingsURLString];
+        [[UIApplication sharedApplication] openURL:url];
+    }
+}
+
 #pragma mark -
 #pragma mark === Utility methods ===
 #pragma mark -
 
+- (void)showAlertForCameraError:(NSError *)error
+{
+    NSString *buttonTitle = nil;
+    NSString *message = error.localizedFailureReason ? error.localizedFailureReason : error.localizedDescription;
+    
+    if ((error.code == AVErrorApplicationIsNotAuthorizedToUseDevice) &&
+        UIApplicationOpenSettingsURLString)
+    {
+        // Starting with iOS 8 we can directly open the settings bundle
+        // for this App so add a settings button to the alert view.
+        buttonTitle = NSLocalizedString(@"AlertViewSettingsButton", @"Settings");
+    }
+
+    UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:NSLocalizedString(@"AlertViewTitleCameraError", @"Camera Error")
+                                                        message:message
+                                                       delegate:self
+                                              cancelButtonTitle:NSLocalizedString(@"AlertViewCancelButton", @"Cancel")
+                                              otherButtonTitles:buttonTitle, nil];
+    [alertView show];
+}
+
 - (void)startRunning
 {
     self.codeObjects = nil;

QReader/QReader/en.lproj/Localizable.strings

@@ -0,0 +1,11 @@
+/* 
+  Localizable.strings
+  QReader
+
+  Created by Keith Harrison on 28/08/2014.
+  Copyright (c) 2014 Keith Harrison. All rights reserved.
+*/
+
+"AlertViewTitleCameraError" = "Camera Error";
+"AlertViewCancelButton" = "Cancel";
+"AlertViewSettingsButton" = "Settings";

QReader/README

@@ -1,8 +1,14 @@
 =======================================================================
 QReader - Reading QR Codes
+Version 1.1   28 Aug 2014   Add handling of camera privacys settings.
 Version 1.0   12 May 2014   Initial version.
 =======================================================================
 
 Example of how to use AVFoundation to capture QR codes. See the following post for details:
 
-http://useyourloaf.com/blog/2014/05/13/reading-qr-codes.html
+http://useyourloaf.com/blog/2014/05/13/reading-qr-codes.html
+
+For details on adding an alert view to warn the user when the camera cannot be
+accessed and directly launch the settings (requires iOS 8) see the following post:
+
+http://useyourloaf.com/blog/2014/08/28/open-settings-url.html