Upstream Chrome on iOS source code [7/11].

ios/chrome/browser/ui/settings/cells/byo_textfield_item.mm

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "ios/chrome/browser/ui/settings/cells/byo_textfield_item.h"
+
+#include "base/logging.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
+namespace {
+// Padding used on the leading and trailing edges of the cell.
+const CGFloat kHorizontalPadding = 16;
+}  // namespace
+
+@interface BYOTextFieldCell ()
+
+// The text field installed in this cell.
+@property(nonatomic, strong) UITextField* textField;
+
+// The constraints set on the textfield.
+@property(nonatomic, strong) NSArray<NSLayoutConstraint*>* textFieldConstraints;
+
+// Sets up the text field and displays it inside the cell.
+- (void)installTextField:(UITextField*)textField;
+
+@end
+
+@implementation BYOTextFieldItem
+
+@synthesize textField = _textField;
+
+- (instancetype)initWithType:(NSInteger)type {
+  self = [super initWithType:type];
+  if (self) {
+    self.cellClass = [BYOTextFieldCell class];
+  }
+  return self;
+}
+
+- (void)configureCell:(BYOTextFieldCell*)cell {
+  [super configureCell:cell];
+  [cell installTextField:self.textField];
+}
+
+@end
+
+@implementation BYOTextFieldCell
+
+@synthesize textField = _textField;
+@synthesize textFieldConstraints = _textFieldConstraints;
+
+- (void)installTextField:(UITextField*)textField {
+  // Make sure not text field is still installed.
+  [self uninstallTextField];
+
+  // If there is no text field to install, return.
+  if (!textField) {
+    return;
+  }
+
+  // Store the text field.
+  self.textField = textField;
+
+  // Add it to the content view.
+  textField.translatesAutoresizingMaskIntoConstraints = NO;
+  UIView* contentView = self.contentView;
+  [contentView addSubview:textField];
+
+  // Store the constraints.
+  self.textFieldConstraints = @[
+    [textField.topAnchor constraintEqualToAnchor:contentView.topAnchor],
+    [textField.bottomAnchor constraintEqualToAnchor:contentView.bottomAnchor],
+    [textField.leadingAnchor constraintEqualToAnchor:contentView.leadingAnchor
+                                            constant:kHorizontalPadding],
+    [textField.trailingAnchor constraintEqualToAnchor:contentView.trailingAnchor
+                                             constant:-kHorizontalPadding],
+  ];
+
+  // Activate the constraints.
+  [NSLayoutConstraint activateConstraints:self.textFieldConstraints];
+}
+
+- (void)uninstallTextField {
+  // Deactivate the constraints.
+  [NSLayoutConstraint deactivateConstraints:self.textFieldConstraints];
+  // Release the constraints.
+  self.textFieldConstraints = nil;
+  // Remove the text field from the content view.
+  [self.textField removeFromSuperview];
+  // Release the text field.
+  self.textField = nil;
+}
+
+- (void)prepareForReuse {
+  [super prepareForReuse];
+  [self uninstallTextField];
+}
+
+@end