NSMutableAttributedString

• 繼承自NSAttributedString
• 使用場合
  • UILabel - attributedText
  • UITextField - attributedPlaceholder

NSAttributedString常見用法示例

• NSAttributedString創建及初始化

NSMutableDictionary *attributes = [NSMutableDictionary dictionary];
attributes[NSForegroundColorAttributeName] = [UIColor yellowColor];
attributes[NSBackgroundColorAttributeName] = [UIColor redColor];
attributes[NSUnderlineStyleAttributeName] = @YES;
NSAttributedString *string = [[NSAttributedString alloc] initWithString:@"123" attributes:attributes];

• 圖文混排

  UILabel *label = [[UILabel alloc] init];
  label.frame = CGRectMake(100, 100, 200, 25);
  label.backgroundColor = [UIColor redColor];
  label.font = [UIFont systemFontOfSize:14];
  [self.view addSubview:label];
  
  // 圖文混排
  NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] init];
  // 1 - 你好
  NSAttributedString *first = [[NSAttributedString alloc] initWithString:@"你好"];
  [attributedText appendAttributedString:first];
  
  // 2 - 圖片
  // 帶有圖片的附件對象
  NSTextAttachment *attachment = [[NSTextAttachment alloc] init];
  attachment.image = [UIImage imageNamed:@"header_cry_icon"];
  CGFloat lineH = label.font.lineHeight;
  attachment.bounds = CGRectMake(0, - ((label.xmg_height - lineH) * 0.5 - 1), lineH, lineH);
  // 將附件對象包裝成一個屬性文字
  NSAttributedString *second = [NSAttributedString attributedStringWithAttachment:attachment];
  [attributedText appendAttributedString:second];
  
  // 3 - 哈哈哈
  NSAttributedString *third = [[NSAttributedString alloc] initWithString:@"哈哈哈"];
  [attributedText appendAttributedString:third];
  
  label.attributedText = attributedText;
  

• 一個Label顯示多行不同字體的文字

UILabel *label = [[UILabel alloc] init];
// 設置屬性文字
NSString *text = @"你好\n哈哈哈";
NSMutableAttributedString *attributedText = [[NSMutableAttributedString alloc] initWithString:text];
[attributedText addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:10] range:NSMakeRange(0, text.length)];
[attributedText addAttribute:NSFontAttributeName value:[UIFont boldSystemFontOfSize:13] range:NSMakeRange(3, 3)];
label.attributedText = attributedText;
// 其他設置
label.numberOfLines = 0;
label.textAlignment = NSTextAlignmentCenter;
label.frame = CGRectMake(0, 0, 100, 40);
[self.view addSubview:label];
self.navigationItem.titleView = label;

• 富文本占位文字

  // 設置range范圍的屬性, 重復設置同一個范圍的屬性, 最后一次設置才是有效的(之前的設置會被覆蓋掉)
  - (void)setAttributes:(nullable NSDictionary<NSString *, id> *)attrs range:(NSRange)range;
  
  // 添加range范圍的屬性, 同一個范圍, 可以不斷累加屬性
  - (void)addAttribute:(NSString *)name value:(id)value range:(NSRange)range;
  - (void)addAttributes:(NSDictionary<NSString *, id> *)attrs range:(NSRange)range;
  

  // 創建富文本
  NSMutableAttributedString *string = [[NSMutableAttributedString alloc] initWithString:self.placeholder];
  
  // 設置第一種屬性
  NSMutableDictionary *attributes = [NSMutableDictionary dictionary];
  attributes[NSForegroundColorAttributeName] = [UIColor yellowColor];
  [string setAttributes:attributes range:NSMakeRange(0, 1)];
  
  // 設置第二種屬性
  NSMutableDictionary *attributes2 = [NSMutableDictionary dictionary];
  attributes2[NSBackgroundColorAttributeName] = [UIColor redColor];
  attributes2[NSUnderlineStyleAttributeName] = @YES;
  
  // 將區域中的顏色屬性替換為新的屬性
  [string setAttributes:attributes2 range:NSMakeRange(0, 2)];
  
  // 為富文本增加新的屬性
  [string addAttribute:NSForegroundColorAttributeName value:[UIColor yellowColor] range:NSMakeRange(0, 1)];
  [string addAttribute:NSBackgroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(0, 1)];
  [string addAttribute:NSUnderlineStyleAttributeName value:@YES range:NSMakeRange(1, 1)];
  
  // 設置富文本占位文字
  textField.attributedPlaceholder = string;