material-components_material-components-ios/components/NavigationBar/examples/NavigationBarLayoutExample.m

/*
 Copyright 2017-present the Material Components for iOS authors. All Rights Reserved.
 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 http://www.apache.org/licenses/LICENSE-2.0
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "MaterialIcons+ic_arrow_back.h"
#import "MaterialNavigationBar.h"
#import "MaterialTextFields.h"
#import "MaterialNavigationBar+ColorThemer.h"
#import <MDFInternationalization/MDFInternationalization.h>

@interface NavigationBarLayoutExample : UIViewController <UITextFieldDelegate>

@property(nonatomic, strong) MDCNavigationBar *navigationBar;
@property(nonatomic, strong) MDCTextInputControllerLegacyDefault *leadingItemController;
@property(nonatomic, strong) MDCTextField *leadingItemField;
@property(nonatomic, strong) MDCTextInputControllerLegacyDefault *trailingItemController;
@property(nonatomic, strong) MDCTextField *trailingItemField;
@property(nonatomic, strong) MDCTextInputControllerLegacyDefault *titleController;
@property(nonatomic, strong) MDCTextField *titleField;
@property(nonatomic, weak) UIBarButtonItem *trailingBarButtonItem;
@property(nonatomic, weak) UIBarButtonItem *leadingBarButtonItem;

@end
@implementation NavigationBarLayoutExample

- (void)viewDidLoad {
  [super viewDidLoad];

  self.title = @"Title";
  self.view.backgroundColor = UIColor.whiteColor;

  self.navigationBar = [[MDCNavigationBar alloc] initWithFrame:CGRectZero];
  self.navigationBar.translatesAutoresizingMaskIntoConstraints = NO;
  [self.navigationBar observeNavigationItem:self.navigationItem];
  [self.view addSubview:self.navigationBar];

  id<MDCColorScheming> colorScheme = [[MDCSemanticColorScheme alloc] init];
  [MDCNavigationBarColorThemer applySemanticColorScheme:colorScheme
                                        toNavigationBar:self.navigationBar];

  UIBarButtonItem *leadingButtonItem =
      [[UIBarButtonItem alloc] initWithTitle:@"L"
                                       style:UIBarButtonItemStylePlain
                                      target:nil
                                      action:nil];
  UIBarButtonItem *trailingButtonItem =
      [[UIBarButtonItem alloc] initWithTitle:@"T"
                                       style:UIBarButtonItemStylePlain
                                      target:nil
                                      action:nil];

  self.leadingBarButtonItem = leadingButtonItem;
  self.trailingBarButtonItem = trailingButtonItem;
  self.navigationItem.hidesBackButton = NO;
  self.navigationItem.leftBarButtonItems = @[ leadingButtonItem ];
  self.navigationItem.rightBarButtonItem = trailingButtonItem;

  self.leadingItemField = [[MDCTextField alloc] initWithFrame:CGRectZero];
  self.leadingItemField.translatesAutoresizingMaskIntoConstraints = NO;
  self.leadingItemField.delegate = self;
  self.leadingItemField.text = @"L";

  self.leadingItemController =
      [[MDCTextInputControllerLegacyDefault alloc] initWithTextInput:self.leadingItemField];

  self.trailingItemField = [[MDCTextField alloc] initWithFrame:CGRectZero];
  self.trailingItemField.translatesAutoresizingMaskIntoConstraints = NO;
  self.trailingItemField.delegate = self;
  self.trailingItemField.text = @"T";
  self.trailingItemController =
      [[MDCTextInputControllerLegacyDefault alloc] initWithTextInput:self.trailingItemField];

  self.titleField = [[MDCTextField alloc] initWithFrame:CGRectZero];
  self.titleField.translatesAutoresizingMaskIntoConstraints = NO;
  self.titleField.delegate = self;
  self.titleField.text = self.title;
  self.titleController =
      [[MDCTextInputControllerLegacyDefault alloc] initWithTextInput:self.titleField];

  [self.view addSubview:self.leadingItemField];
  [self.view addSubview:self.trailingItemField];
  [self.view addSubview:self.titleField];

#if defined(__IPHONE_11_0) && (__IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_11_0)
  if (@available(iOS 11.0, *)) {
    [self.view.safeAreaLayoutGuide.topAnchor constraintEqualToAnchor:self.navigationBar.topAnchor].active = YES;
  } else {
#endif
    [NSLayoutConstraint constraintWithItem:self.topLayoutGuide
                                 attribute:NSLayoutAttributeBottom
                                 relatedBy:NSLayoutRelationEqual
                                    toItem:self.navigationBar
                                 attribute:NSLayoutAttributeTop
                                multiplier:1.0
                                  constant:0].active = YES;
#if defined(__IPHONE_11_0) && (__IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_11_0)
  }
#endif
  [NSLayoutConstraint constraintWithItem:self.navigationBar
                               attribute:NSLayoutAttributeBottom
                               relatedBy:NSLayoutRelationEqual
                                  toItem:self.leadingItemField
                               attribute:NSLayoutAttributeTop
                              multiplier:1.0
                                constant:0].active = YES;
  [NSLayoutConstraint constraintWithItem:self.leadingItemField
                               attribute:NSLayoutAttributeBottom
                               relatedBy:NSLayoutRelationEqual
                                  toItem:self.titleField
                               attribute:NSLayoutAttributeTop
                              multiplier:1.0
                                constant:0].active = YES;
  [NSLayoutConstraint constraintWithItem:self.titleField
                               attribute:NSLayoutAttributeBottom
                               relatedBy:NSLayoutRelationEqual
                                  toItem:self.trailingItemField
                               attribute:NSLayoutAttributeTop
                              multiplier:1.0
                                constant:0].active = YES;

  NSDictionary *viewsBindings = NSDictionaryOfVariableBindings(_navigationBar, _leadingItemField,
                                                               _titleField, _trailingItemField);
  [NSLayoutConstraint
      activateConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_navigationBar]|"
                                                                  options:0
                                                                  metrics:nil
                                                                    views:viewsBindings]];
  [NSLayoutConstraint
      activateConstraints:[NSLayoutConstraint
                              constraintsWithVisualFormat:@"H:|-16-[_leadingItemField]-16-|"
                                                  options:0
                                                  metrics:nil
                                                    views:viewsBindings]];
  [NSLayoutConstraint
      activateConstraints:[NSLayoutConstraint
                              constraintsWithVisualFormat:@"H:|-16-[_titleField]-16-|"
                                                  options:0
                                                  metrics:nil
                                                    views:viewsBindings]];
  [NSLayoutConstraint
      activateConstraints:[NSLayoutConstraint
                              constraintsWithVisualFormat:@"H:|-16-[_trailingItemField]-16-|"
                                                  options:0
                                                  metrics:nil
                                                    views:viewsBindings]];
}

- (BOOL)prefersStatusBarHidden {
  return YES;
}

- (void)viewWillAppear:(BOOL)animated {
  [super viewWillAppear:animated];

  [self.navigationController setNavigationBarHidden:YES animated:animated];
}

- (void)didTapBackButton {
  [self.navigationController popViewControllerAnimated:YES];
}

#pragma mark - <UITextFieldDelegate>

- (BOOL)textField:(UITextField *)textField
    shouldChangeCharactersInRange:(NSRange)range
                replacementString:(NSString *)string {
  NSString *finishedString =
      [textField.text stringByReplacingCharactersInRange:range withString:string];

  // MDCNavigationBar doesn't handle BarButtonItems with no image and zero-length strings
  if (finishedString.length == 0) {
    finishedString = @" ";
  }
  if (textField == self.leadingItemField) {
    NSMutableArray<UIBarButtonItem *> *leadingItems =
        [self.navigationItem.leftBarButtonItems mutableCopy];
    [leadingItems removeLastObject];
    [leadingItems addObject:[[UIBarButtonItem alloc] initWithTitle:finishedString
                                                             style:UIBarButtonItemStylePlain
                                                            target:nil
                                                            action:nil]];
    self.navigationItem.leftBarButtonItems = leadingItems;
  } else if (textField == self.trailingItemField) {
    // We need to allocate and reassign because MDCNavigationBar does not adjust its layout
    // when the existing items change their title
    self.navigationItem.rightBarButtonItem =
        [[UIBarButtonItem alloc] initWithTitle:finishedString
                                         style:UIBarButtonItemStylePlain
                                        target:nil
                                        action:nil];
  } else if (textField == self.titleField) {
    self.title = finishedString;
  }
  return YES;
}

@end

@implementation NavigationBarLayoutExample (CatalogByConvention)

+ (NSArray *)catalogBreadcrumbs {
  return @[ @"Navigation Bar", @"Navigation Bar Item Layout" ];
}

+ (BOOL)catalogIsPrimaryDemo {
  return NO;
}

- (BOOL)catalogShouldHideNavigation {
  return YES;
}

+ (BOOL)catalogIsPresentable {
  return YES;
}

@end