objective-c - UIScrollView 中的中心行按钮

Question

我在 UIScrollView 中动态添加按钮，但有些 View 只有两个按钮，有些有 10 个。我想在 ScrollView 中将按钮居中，这样看起来我不是从左到右构建它们的。我已经尝试了 SO 的几种技巧，但似乎没有任何效果。设置内容偏移量是我的第一种方法，但没有达到我想要的效果。

这是我使用的代码:

- (void)addButton:(UIButton *)button {
CGFloat contentWidth = 0.0f;
CGRect buttonFrame = button.frame;   
if ([_scrollView.subviews count] == 0) {

    buttonFrame.origin.x = self.contentIndicatorWidth + kButtonSeperator;
    contentWidth = self.contentIndicatorWidth + buttonFrame.size.width + self.contentIndicatorWidth;
} else {
    contentWidth = _scrollView.contentSize.width;
    UIButton *lastButton = [_scrollView.subviews lastObject];
    buttonFrame.origin.x = lastButton.frame.origin.x + lastButton.frame.size.width + kButtonSeperator;
    contentWidth += buttonFrame.size.width + kButtonSeperator;
}
button.frame = buttonFrame;
[_scrollView addSubview:button];
 _scrollView.contentSize = CGSizeMake(contentWidth *kContentMultiplicityFactor, _scrollView.frame.size.height);
 [_buttons setValue:button forKey:button.titleLabel.text];
totalWidth = contentWidth;

//[_scrollView scrollRectToVisible:[self getButtonAtIndex:0].frame animated:YES];

Answer 1

添加按钮后调用此方法:

- (void)centerButtons:(NSArray*)buttons {
  CGSize scrollViewSize = _scrollView.bounds.size;

  // Measure the total width taken by the buttons
  CGFloat width = 0;
  for (UIButton* b in buttons)
    width += b.bounds.size.width + kButtonSeparator;
  if (width > kButtonSeparator)
    width -= kButtonSeparator;

  // If the buttons width is shorter than the visible bounds, adjust origin
  CGFloat origin = 0;
  if (width < scrollViewSize.width)
    origin = (scrollViewSize.width - width) / 2.f;

  // Place buttons
  CGFloat x = origin;
  CGFloat y = 0;
  for (UIButton* b in buttons) {
    b.center = CGPointMake(x + b.bounds.size.width/2.f, y + b.bounds.size.height/2.f);
    x += b.bounds.size.width + kButtonSeparator;
  }

  _scrollView.contentSize = CGSizeMake(MAX(scrollViewSize.width, width), scrollViewSize.height);
}