ios - UIScrollView 在方向改变之前不滚动

Question

我有一个 UIScrollView 动态添加到主视图中，我用小的 UIView 对象填充它。我将其 contentSize 设置为大于设备分辨率的值，但在更改设备方向之前我无法滚动它。

如何让它在方向改变之前滚动？

后期编辑:

我意识到问题来 self 正在添加的某些 subview ，更具体地说是来自为这些 subview 添加一些约束:

这是我添加 subview 的代码(该方法被调用了大约 10-20 次):

-(void) addShelve:(NSInteger) index
{
FSShelf *shelf = [[FSShelf alloc] initWithFrame:CGRectMake(0, index * [FSConstants getShelfVerticalDistance], 0, 0)];
[shelves addObject:shelf];

[shelfView addSubview:shelf];
[shelf addShelfConstraints];
}

FSShelf 是 UIView 的子类，shelfView 是我的 UIScrollView 的子类。

下面是在 addShelfContraints 中添加的约束:

    [self.superview addConstraint:[FSUtils getWidthConstraintFor:self.superview with:self constant: -2 * ([FSConstants getShelveMargin])]];
    [self addConstraint:[FSUtils getSelfHeightConstraintFor:self constant:30]];
    [self.superview addConstraint:[FSUtils getCenterXConstraintFor:self.superview with:self constant:0]];

FSUtils 类中用于添加约束的方法:

+ (NSLayoutConstraint *)getSelfHeightConstraintFor:(UIView *)view constant:(CGFloat)constant
{
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:view
                                                                  attribute:NSLayoutAttributeHeight
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:nil
                                                                  attribute:NSLayoutAttributeNotAnAttribute
                                                                 multiplier:1.0
                                                                   constant:constant];
    return constraint;
}

+ (NSLayoutConstraint *)getCenterXConstraintFor:(UIView *)superView with:(UIView *)subView constant:(CGFloat)constant
{
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:subView
                                                                  attribute:NSLayoutAttributeCenterX
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:superView
                                                                  attribute:NSLayoutAttributeCenterX
                                                                 multiplier:1.0
                                                                   constant:constant];

    return constraint;
}

+ (NSLayoutConstraint *)getWidthConstraintFor:(UIView *)superView with:(UIView *)subView constant:(CGFloat)constant
{
    NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:subView
                                                                  attribute:NSLayoutAttributeWidth
                                                                  relatedBy:NSLayoutRelationEqual
                                                                     toItem:superView
                                                                  attribute:NSLayoutAttributeWidth
                                                                 multiplier:1.0
                                                                   constant:constant];
    return constraint;
}

你注意到这些约束有什么问题吗？

Answer 1

在您的单次点击中，尝试像这样创建

UIScrollView * scrollview = [[UIScrollView alloc]init];
CGRect viewFrame = self.view.frame;
[scrollview setFrame:viewFrame];
[scrollview setShowsHorizontalScrollIndicator:YES];
[scrollview setShowsVerticalScrollIndicator:YES];

UIView * view = [[UIView alloc]init];
CGRect viewDoubleFrame = CGRectMake(viewFrame.origin.x,viewFrame.origin.y,viewFrame.size.width * 2,viewFrame.size.height *2);
[view setFrame:viewDoubleFrame];
[view setBackgroundColor:[UIColor darkGrayColor]];

// add your additional components here

[scrollview setContentSize:CGSizeMake(view.frame.size.width,view.frame.size.height)];
[scrollview addSubview:view];

[self.view addSubview:scrollview];