《精通 iOS 开发》第 09 章学习笔记

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Font应用的基础框架

1.工厂方法代码示例：

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+ (instancetype)sharedFavoritesList {
  static BIDFavoritesList *shared = nil;
  static dispatch_once_t onceToken;

  dispatch_once(&onceToken, ^{
    shared = [[self alloc] init];
  });

  return shared;
}

2.读取用户偏好设置代码示例：

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- (instancetype)init {
  self = [super init];
  if (self) {
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
    NSArray *storedFavorites = [defaults objectForKey:@"favorites"];

    if (storedFavorites) {
      self.favorites = [storedFavorites mutableCopy];
    } else {
      self.favorites = [NSMutableArray array];
    }
  }
  return self;
}

3.保存用户偏好设置代码示例：

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- (void)moveItemAtIndex:(NSInteger)from toIndex:(NSInteger)to {
  id item = _favorites[from];
  [_favorites removeObjectAtIndex:from];
  [_favorites insertObject:item atIndex:to];
  [self saveFavorites];
}

创建根视图控制器

1.获取所有已知字体名字：

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- (void)viewDidLoad {
  [super viewDidLoad];

  self.familyNames = [[UIFont familyNames] sortedArrayUsingSelector:@selector(compare:)];

  UIFont *preferredTableViewFont = [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];

  self.cellPointSize = preferredTableViewFont.pointSize;
  self.favoritesList = [BIDFavoritesList sharedFavoritesList];
}

2.设置分区标题：

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- (NSString *)tableView:(UITableView *)tableView
titleForHeaderInSection:(NSInteger)section {
  if (section == 0) {
    return @"All Font Families";
  } else {
    return @"My Favorite Fonts";
  }
}

3.根据字体大小设置每行高度：

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- (CGFloat)tableView:(UITableView *)tableView
    heightForRowAtIndexPath:(NSIndexPath *)indexPath {
  if (indexPath.section == 0) {
    UIFont *font = [self fontForDisplayAtIndexPath:indexPath];
    return 25 + font.ascender - font.descender;
  } else {
    return tableView.rowHeight;
  }
}

创建字体列表视图控制器

1.添加编辑按钮：

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- (void)viewDidLoad {
  [super viewDidLoad];

  UIFont *preferredTableViewFont =
      [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];

  self.cellPointSize = preferredTableViewFont.pointSize;

  if (self.showsFavorites) {
    self.navigationItem.rightBarButtonItem = self.editButtonItem;
  }
}

2.在视图将要出现时，重载数据：

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- (void)viewWillAppear:(BOOL)animated {
  if (self.showsFavorites) {
    self.fontNames = [BIDFavoritesList sharedFavoritesList].favorites;
    [self.tableView reloadData];
  }
}

3.使每行数据都能编辑：

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- (BOOL)tableView:(UITableView *)tableView
    canEditRowAtIndexPath:(NSIndexPath *)indexPath {
  // Return NO if you do not want the specified item to be editable.
  return self.showsFavorites;
}

4.删除某行数据：

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- (void)tableView:(UITableView *)tableView
    commitEditingStyle:(UITableViewCellEditingStyle)editingStyle
     forRowAtIndexPath:(NSIndexPath *)indexPath {
  if (!self.showsFavorites) {
    return;
  }
  if (editingStyle == UITableViewCellEditingStyleDelete) {
    NSString *favorite = self.fontNames[indexPath.row];
    [[BIDFavoritesList sharedFavoritesList] removeFavorite:favorite];
    self.fontNames = [BIDFavoritesList sharedFavoritesList].favorites;

    // Delete the row from the data source
    [tableView deleteRowsAtIndexPaths:@[ indexPath ]
                     withRowAnimation:UITableViewRowAnimationFade];
    //} else if (editingStyle == UITableViewCellEditingStyleInsert) {
    // Create a new instance of the appropriate class, insert it into the array,
    // and add a new row to the table view
  }
}

5.调整某行数据：

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- (void)tableView:(UITableView *)tableView
    moveRowAtIndexPath:(NSIndexPath *)fromIndexPath
           toIndexPath:(NSIndexPath *)toIndexPath {
  [[BIDFavoritesList sharedFavoritesList] moveItemAtIndex:fromIndexPath.row
                                                  toIndex:toIndexPath.row];
  self.fontNames = [BIDFavoritesList sharedFavoritesList].favorites;
}

6.场景跳转时的数据处理：

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- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
  NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
  UIFont *font = [self fontForDisplayAtIndexPath:indexPath];

  [segue.destinationViewController navigationItem].title = font.fontName;

  if ([segue.identifier isEqualToString:@"ShowFontSizes"]) {
    BIDFontSizesViewController *sizeVC = segue.destinationViewController;
    sizeVC.font = font;
  } else {
    BIDFontInfoViewController *infoVC = segue.destinationViewController;
    infoVC.font = font;
    infoVC.favorite = [[BIDFavoritesList sharedFavoritesList]
                           .favorites containsObject:font.fontName];
  }
}

创建字体尺寸视图控制器

1.字体大小数组初始化：

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- (NSArray *)pointSizes {
  static NSArray *pointSizes = nil;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    pointSizes = @[
      @9,
      @10,
      @11,
      @12,
      @13,
      @14,
      @18,
      @24,
      @36,
      @48,
      @64,
      @72,
      @96,
      @144
    ];
  });
  return pointSizes;
}