以 Autolayout 视觉形式调整子视图的大小

Question

我未能将我的应用从 Autoresize 迁移到 Autolayout 机制。我所需要的只是一个具有动态大小和子视图的视图，它们将连接到与它们的父视图相同大小的左上角。在 IB 中，我将 PieView（我的超级视图）的大小设置为 186x186。并让 IB 生成所有需要的约束（我将在代码中创建新的约束）：

PieView.m -updateConstraints()

- (void)updateConstraints {
[super updateConstraints];
[self removeConstraintsAffectingViewAndSubviews];
[self setTranslatesAutoresizingMaskIntoConstraints:NO];

CGFloat sizeCoef = 0.7f;
CGFloat percent = [self.category getFillinPercent] / 100.0f;
percent = percent > 1.0f ? 1.0f : percent;
sizeCoef += (1.0f - sizeCoef) * percent;

NSLayoutConstraint *width = [NSLayoutConstraint constraintWithItem:self
                                                         attribute:NSLayoutAttributeWidth
                                                         relatedBy:NSLayoutRelationEqual
                                                            toItem:nil
                                                         attribute:NSLayoutAttributeNotAnAttribute
                                                        multiplier:1.0f
                                                          constant:100.f];//kDiameter * sizeCoef];

NSLayoutConstraint *height = [NSLayoutConstraint constraintWithItem:self
                                                          attribute:NSLayoutAttributeHeight
                                                          relatedBy:NSLayoutRelationEqual
                                                             toItem:nil
                                                          attribute:NSLayoutAttributeNotAnAttribute
                                                         multiplier:1.0f
                                                           constant:100.0f];//kDiameter * sizeCoef];
//_imgEmptyCircle, _imgFullCircle - UIImageViews
NSDictionary *views = NSDictionaryOfVariableBindings(_imgEmptyCircle, _imgFullCircle, self);
NSDictionary *metrics = @{@"height":@100.0};

[self addConstraints:@[width, height]];

NSString *visualForm = @"H:|[_imgEmptyCircle(height)][_imgFullCircle(height)]|";
NSArray *horizontalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:visualForm
                                                                     options:0
                                                                     metrics:metrics
                                                                       views:views];
visualForm = @"V:|[_imgEmptyCircle(height)][_imgFullCircle(height)]|";
NSArray *verticalConstraints = [NSLayoutConstraint constraintsWithVisualFormat:visualForm
                                                                      options:0
                                                                      metrics:metrics
                                                                        views:views];
[self addConstraints:verticalConstraints];
[self addConstraints:horizontalConstraints];

}

结果真让我吃惊。蓝色的如我所愿正确显示，但绿色的有奇怪的行为。

当然我有错误：无法同时满足约束。
First imageView：
NSIBPrototypingLayoutConstraint:0xa2795d0 'IB 在构建时为固定框架视图自动生成' V:[UIImageView:0x8a37150(186)]>
NSLayoutConstraint:0xa0305c0 V:[UIImageView:0x8a37150(100)]
第二个 imageView:
同一个
可能是 PieView:
( NSLayoutConstraint:0x8a40750 V:[CEPieView:0x8a36e50(100)], NSLayoutConstraint:0xa030570 V:|-(0)-[UIImageView:0x8a37150]（名称：'|':CEPieView:0x8a36e50）， NSLayoutConstraint:0xa0305c0 V:[UIImageView:0x8a37150(100)], NSLayoutConstraint:0xa0305f0 V:[UIImageView:0x8a37150]-(0)-[UIImageView:0xa277cf0]> NSLayoutConstraint:0xa030620 V:[UIImageView:0xa277cf0(100)], NSLayoutConstraint:0xa030650 V:[UIImageView:0xa277cf0]-(0)-| （名称：'|':CEPieView:0x8a36e50） )

请给我建议如何解决它。如何借助 AutoLayout 机制创建和旧的自动调整掩码（UIViewAutoresizingFlexibleHeight、UIViewAutoresizingFlexibleWidth）。任何帮助将不胜感激。

Answer 1

您设置约束的方式是错误的。基本上，您要求超级视图为 100pts x 100pts，并包含两个子视图，每个子视图均为 100pts x 100pts，并且彼此相邻且位于彼此之上。因此，首先您的超级视图必须是 200pts 宽和/或高，然后您不能有两个彼此相邻且位于顶部的视图。 你真正想做的（我认为）是：

NSString *visualForm = @"H:|[_imgFullCircle]|"; // No need to explicitly set the height

然后添加相应的约束，然后：

visualForm = @"H:|[_imgEmptyCircle(height)]|";

并为此添加另一个约束，并为垂直约束做同样的事情。

基本上你会得到：

//_imgEmptyCircle, _imgFullCircle - UIImageViews
NSDictionary *views = NSDictionaryOfVariableBindings(_imgEmptyCircle, _imgFullCircle, self);

[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_imgEmptyCircle]|"
                                                                 options:0
                                                                 metrics:nil
                                                                   views:views]];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[_imgFullCircle]|"
                                                                 options:0
                                                                 metrics:nil
                                                                   views:views]];                                                                       
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_imgEmptyCircle]|"
                                                                 options:0
                                                                 metrics:nil
                                                                   views:views]];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[_imgFullCircle]|"
                                                                 options:0
                                                                 metrics:nil
                                                                   views:views]];