Add setting to AppRTCMobile for iOS, that can change capture resolution.

webrtc/examples/objc/AppRTCMobile/ios/ARDSettingsViewController.m

+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import "ARDSettingsViewController.h"
+#import "ARDMediaConstraintsModel.h"
+
+NS_ASSUME_NONNULL_BEGIN
+@interface ARDSettingsViewController () {
+  ARDMediaConstraintsModel *_mediaConstraintsModel;
+}
+
+@end
+
+@implementation ARDSettingsViewController
+
+- (instancetype)initWithStyle:(UITableViewStyle)style
+        mediaConstraintsModel:(ARDMediaConstraintsModel *)mediaConstraintsModel {
+  self = [super initWithStyle:style];
+  if (self) {
+    _mediaConstraintsModel = mediaConstraintsModel;
+  }
+  return self;
+}
+
+#pragma mark - View lifecycle
+
+- (void)viewDidLoad {
+  [super viewDidLoad];
+  self.title = @"Settings";
+  [self addDoneBarButton];
+}
+
+- (void)viewDidAppear:(BOOL)animated {
+  [super viewDidAppear:animated];
+  [self selectCurrentlyStoredOrDefaultMediaConstraints];
+}
+
+#pragma mark - Data source
+
+- (NSArray<NSString *> *)mediaConstraintsArray {
+  return _mediaConstraintsModel.availableVideoResoultionsMediaConstraints;
+}
+
+#pragma mark -
+
+- (void)addDoneBarButton {
+  UIBarButtonItem *barItem =
+      [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone
+                                                    target:self
+                                                    action:@selector(dismissModally:)];
+  self.navigationItem.leftBarButtonItem = barItem;
+}
+
+- (void)selectCurrentlyStoredOrDefaultMediaConstraints {
+  NSString *currentSelection = [_mediaConstraintsModel currentVideoResoultionConstraintFromStore];
+
+  NSUInteger indexOfSelection = [[self mediaConstraintsArray] indexOfObject:currentSelection];
+  NSIndexPath *pathToBeSelected = [NSIndexPath indexPathForRow:indexOfSelection inSection:0];
+  [self.tableView selectRowAtIndexPath:pathToBeSelected
+                              animated:NO
+                        scrollPosition:UITableViewScrollPositionNone];
+  // Manully invoke the delegate method because the previous invocation will not.
+  [self tableView:self.tableView didSelectRowAtIndexPath:pathToBeSelected];
+}
+
+#pragma mark - Dismissal of view controller
+
+- (void)dismissModally:(id)sender {
+  [self dismissViewControllerAnimated:YES completion:nil];
+}
+
+#pragma mark - Table view data source
+
+- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
+  return 1;
+}
+
+- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
+  return self.mediaConstraintsArray.count;
+}
+
+#pragma mark - Table view delegate
+
+- (BOOL)sectionIsMediaConstraints:(int)section {
+  return section == 0;
+}
+
+- (BOOL)indexPathIsMediaConstraints:(NSIndexPath *)indexPath {
+  return [self sectionIsMediaConstraints:indexPath.section];
+}
+
+- (nullable NSString *)tableView:(UITableView *)tableView
+         titleForHeaderInSection:(NSInteger)section {
+  if ([self sectionIsMediaConstraints:section]) {
+    return @"Media constraints";
+  }
+  return @"";
+}
+
+- (UITableViewCell *)tableView:(UITableView *)tableView
+         cellForRowAtIndexPath:(NSIndexPath *)indexPath {
+  if ([self indexPathIsMediaConstraints:indexPath]) {
+    return [self mediaConstraintsTableViewCellForTableView:tableView atIndexPath:indexPath];
+  }
+  return [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
+                                reuseIdentifier:@"identifier"];
+}
+
+- (nullable NSIndexPath *)tableView:(UITableView *)tableView
+           willSelectRowAtIndexPath:(nonnull NSIndexPath *)indexPath {
+  if ([self indexPathIsMediaConstraints:indexPath]) {
+    return [self tableView:tableView willDeselectMediaConstraintsRowAtIndexPath:indexPath];
+  }
+  return indexPath;
+}
+
+- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
+  if ([self indexPathIsMediaConstraints:indexPath]) {
+    [self tableView:tableView didSelectMediaConstraintsCellAtIndexPath:indexPath];
+  }
+}
+
+#pragma mark - Table view delegate(Media Constraints)
+
+- (UITableViewCell *)mediaConstraintsTableViewCellForTableView:(UITableView *)tableView
+                                                   atIndexPath:(NSIndexPath *)indexPath {
+  NSString *dequeueIdentifier = @"ARDSettingsMediaConstraintsViewCellIdentifier";
+  UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:dequeueIdentifier];
+  if (!cell) {
+    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
+                                  reuseIdentifier:dequeueIdentifier];
+  }
+  cell.textLabel.text = self.mediaConstraintsArray[indexPath.row];
+  return cell;
+}
+
+- (void)tableView:(UITableView *)tableView
+    didSelectMediaConstraintsCellAtIndexPath:(NSIndexPath *)indexPath {
+  UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
+  cell.accessoryType = UITableViewCellAccessoryCheckmark;
+
+  NSString *mediaConstraintsString = self.mediaConstraintsArray[indexPath.row];
+  [_mediaConstraintsModel storeVideoResoultionConstraint:mediaConstraintsString];
+}
+
+- (NSIndexPath *)tableView:(UITableView *)tableView
+    willDeselectMediaConstraintsRowAtIndexPath:(NSIndexPath *)indexPath {
+  NSIndexPath *oldSelection = [tableView indexPathForSelectedRow];
+  UITableViewCell *cell = [tableView cellForRowAtIndexPath:oldSelection];
+  cell.accessoryType = UITableViewCellAccessoryNone;
+  return indexPath;
+}
+
+@end
+NS_ASSUME_NONNULL_END