ios - 展开有关在自动布局中更改方向和屏幕尺寸的 View

Question

我有一个 UIImageView，我需要在更改方向和屏幕尺寸时扩展(高度和宽度)。我为此使用了自动布局约束。

    topImageView.contentMode = UIViewContentModeScaleAspectFit;
    topImageView.backgroundColor = [UIColor clearColor];
    topImageView.layer.cornerRadius = 5.0f;
    topImageView.clipsToBounds = YES;
    topImageView.translatesAutoresizingMaskIntoConstraints = NO;

    if(login_DO.logoPath)
        [topImageView loadImage:login_DO.logoPath];

    [self.view addSubview:topImageView];

    NSArray *horizontalConstraints =
    [NSLayoutConstraint constraintsWithVisualFormat:[NSString stringWithFormat:@"H:|-(%i)-[topImageView(%f)]",X_OFFSET,VIEW_FRAME_WIDTH-X_OFFSET*2]
                                            options:0 metrics:nil views:@{@"topImageView": topImageView}];

    NSArray *verticalConstraints =
    [NSLayoutConstraint constraintsWithVisualFormat:[NSString stringWithFormat:@"V:|-(%f)-[topImageView(80)]",navHeight]
                                            options:0 metrics:nil views:@{@"topImageView": topImageView}];

    [self.view addConstraints:horizontalConstraints];
    [self.view addConstraints:verticalConstraints];    

    NSLayoutConstraint *leadingMarginForImageConstraint = [NSLayoutConstraint
                                                 constraintWithItem:topImageView attribute:NSLayoutAttributeLeadingMargin
                                                 relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:self.view attribute:
                                                 NSLayoutAttributeLeadingMargin multiplier:1.0 constant:X_OFFSET];

    NSLayoutConstraint *topMarginForImageConstraint = [NSLayoutConstraint
                                                           constraintWithItem:topImageView attribute:NSLayoutAttributeTopMargin
                                                           relatedBy:NSLayoutRelationGreaterThanOrEqual toItem:self.view attribute:
                                                           NSLayoutAttributeTopMargin multiplier:1.0 constant:VIEW_FRAME_WIDTH-X_OFFSET*2];

    [self.view addConstraints:@[ leadingMarginForImageConstraint,
                                 topMarginForImageConstraint]];

但是图片没有展开。我是自动布局的新手。我是否缺少任何约束？

Answer 1

您可以将 imageBottomConstraint 从 -navHeight 更改为从底部开始的其他值。避免使用 VIEW_FRAME_WIDTH，因为它会在您改变方向时改变。

UIView *superview = self.view;
 NSLayoutConstraint *imageTopConstraint = [NSLayoutConstraint
                                                  constraintWithItem:topImageView attribute:NSLayoutAttributeTop
                                                  relatedBy:NSLayoutRelationEqual toItem:superview
                                                  attribute:NSLayoutAttributeTop multiplier:1.0 constant:navHeight];
    NSLayoutConstraint *imageBottomConstraint = [NSLayoutConstraint
                                                     constraintWithItem:topImageView attribute:NSLayoutAttributeBottom
                                                     relatedBy:NSLayoutRelationEqual toItem:superview
                                                     attribute:NSLayoutAttributeBottom multiplier:1.0 constant:-navHeight];
    NSLayoutConstraint *imageLeftConstraint = [NSLayoutConstraint
                                                   constraintWithItem:topImageView attribute:NSLayoutAttributeLeft
                                                   relatedBy:NSLayoutRelationEqual toItem:superview attribute:
                                                   NSLayoutAttributeLeft multiplier:1.0 constant:X_OFFSET];
    NSLayoutConstraint *imageRightConstraint = [NSLayoutConstraint
                                                    constraintWithItem:topImageView attribute:NSLayoutAttributeRight
                                                    relatedBy:NSLayoutRelationEqual toItem:superview attribute:
                                                    NSLayoutAttributeRight multiplier:1.0 constant:-X_OFFSET];
[superview addConstraints:@[imageBottomConstraint ,
                            imageLeftConstraint, imageRightConstraint,
                            imageTopConstraint]];

更多帮助请查看http://www.tutorialspoint.com/ios/ios_auto_layouts.htm

或尝试使用 https://github.com/marcoarment/CompactConstraint

如果有帮助，请告诉我。