什么是"团结"在一起并保持同步一对os UIScrollViews的正确方法？

Question

我想在并行工作的屏幕上有一对scrollview - 称为scrollA和scrollB.当用户滚动/缩放scrollA时,scrollB模仿该行为,缩放和平移相同.反之亦然.

这可能吗？提前致谢.

干杯,道格

Answer 1

根据JoePasq的回答,我会使用KVO并注册观察者,无论你想在每个中模仿哪个键/值对UIScrollView.它看起来像这样(未经测试):

// Do this during initialisation of scrollView2
[scrollView1 addObserver:self
              forKeyPath:@"contentOffset"
                 options:NSKeyValueObservingOptionNew
                 context:NULL];

[scrollView1 addObserver:self
              forKeyPath:@"zoomScale"
                 options:NSKeyValueObservingOptionNew
                 context:NULL];

// Implement this method on scrollView2
- (void)observeValueForKeyPath:(NSString *)keyPath
                      ofObject:(id)object
                        change:(NSDictionary *)change
                       context:(void *)context {

  [self setValue:[change valueForKey:NSKeyValueChangeNewKey] forKey:keyPath];
}