ios - UITableView viewForHeaderInSection UIView 动画问题

Question

我有一个自定义的 UIView，它有两个标签，其中一个是动画的(它像光标一样闪烁，看起来很飞)。这个 View 工作正常，除了当我尝试将它用于 tableView 的标题时；即使我指定了 UIViewAnimationOptionRepeat，动画也不会重复。

我的类(class):

@implementation HXTEST {

  UILabel *cursorLabel;
}

#pragma mark - inits

- (id) initForLabel:(UILabel *)forLabel {

  self = [super init];

  if (self) {

    self.translatesAutoresizingMaskIntoConstraints = NO;

    CGRect abba = [forLabel.text boundingRectWithSize:forLabel.frame.size
                                              options:NSStringDrawingUsesFontLeading
                                           attributes:@{ NSFontAttributeName : forLabel.font}
                                              context:[NSStringDrawingContext new]];

    float width = CGRectGetWidth(abba) * 1.005f;

    self->cursorLabel = [UILabel new];

    self->cursorLabel.textColor = forLabel.textColor;
    self->cursorLabel.font = forLabel.font;
    self->cursorLabel.text = @"▏";
    self->cursorLabel.adjustsFontSizeToFitWidth = forLabel.adjustsFontSizeToFitWidth;
    self->cursorLabel.minimumScaleFactor = forLabel.minimumScaleFactor;
    self->cursorLabel.translatesAutoresizingMaskIntoConstraints = NO;

    [self addSubview:forLabel];
    [self addSubview:self->cursorLabel];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:forLabel
                                                          attribute:NSLayoutAttributeLeading
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:self
                                                          attribute:NSLayoutAttributeLeft
                                                         multiplier:1.f
                                                           constant:0.f]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:forLabel
                                                     attribute:NSLayoutAttributeWidth
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:nil
                                                     attribute:NSLayoutAttributeNotAnAttribute
                                                    multiplier:1.0f
                                                      constant:width]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:forLabel
                                                          attribute:NSLayoutAttributeTop
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:self
                                                          attribute:NSLayoutAttributeTop
                                                         multiplier:1.f
                                                           constant:0.f]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:forLabel
                                                          attribute:NSLayoutAttributeBottom
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:self
                                                          attribute:NSLayoutAttributeBottom
                                                         multiplier:1.f
                                                           constant:0.f]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:self->cursorLabel
                                                     attribute:NSLayoutAttributeLeading
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:forLabel
                                                     attribute:NSLayoutAttributeTrailing
                                                    multiplier:1.f
                                                      constant:0.f]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:self->cursorLabel
                                                     attribute:NSLayoutAttributeWidth
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:nil
                                                     attribute:NSLayoutAttributeNotAnAttribute
                                                    multiplier:1.f
                                                      constant:forLabel.font.pointSize]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:self->cursorLabel
                                                     attribute:NSLayoutAttributeTop
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeTop
                                                    multiplier:1.f
                                                      constant:0.f]];

    [self addConstraint:[NSLayoutConstraint constraintWithItem:self->cursorLabel
                                                     attribute:NSLayoutAttributeBottom
                                                     relatedBy:NSLayoutRelationEqual
                                                        toItem:self
                                                     attribute:NSLayoutAttributeBottom
                                                    multiplier:1.f
                                                      constant:0.f]];
  }

  [UIView animateWithDuration:1.f
                        delay:0.f
                      options:UIViewAnimationOptionRepeat
                   animations:^{

                     self->cursorLabel.alpha = 1.f;
                     self->cursorLabel.alpha = 0.f;
                   }

                   completion:nil];

  return self;
}

@end

是否有关于 tableView 标题及其表示的内容？我应该考虑 UIViewAnimationOptions 的一些其他组合吗？我不应该自动启动动画 block ，而是应该在某些事件(例如 headerView 的外观或类似事件)中触发它？

Answer 1

啊哈!虽然 [UIView areAnimationsEnabled] 默认为 TRUE，但由于某些原因 FALSE。我强制它

[UIView setAnimationsEnabled:YES];

在动画 block 之前，现在一切正常!我不知道为什么它关闭了...