Question

我已将代码减少到生成错误所需的最小值。我有一个tableviewcell完全编程，在内容视图中只有一个图像视图。图像视图应占用整个内容视图。

我约束了图片视图：

到内容视图的顶部
到内容视图的底部
内容视图的前沿
内容视图的后端

最后，我限制了图像视图的高度和宽度基于现有的图像视图比例来看彼此。

- (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier: (NSString *)reuseIdentifier
{

    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
    if (self) {

        self.splashImageView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"img_foo"]];
        self.splashImageView.translatesAutoresizingMaskIntoConstraints = NO;
        self.splashImageView.contentMode = UIViewContentModeScaleAspectFit;

        [self.contentView addSubview:self.splashImageView];
        NSDictionary * viewDictionary = @{@"splashImage":self.splashImageView };
        NSLayoutConstraint * constraint = [NSLayoutConstraint constraintWithItem:self.splashImageView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.splashImageView attribute:NSLayoutAttributeWidth multiplier:(self.splashImageView.image.size.height/self.splashImageView.image.size.width) constant:1];
        [NSLayoutConstraint activateConstraints:@[constraint]];

        NSArray * splashConstraint_H = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[splashImage]|" options:0 metrics:nil views:viewDictionary];
        NSArray * splashConstraint_V = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[splashImage]|" options:0 metrics:nil views:viewDictionary];

        [self.contentView addConstraints:splashConstraint_H];
        [self.contentView addConstraints:splashConstraint_V];
    }
    return self;
}

感知表格单元格的宽度，这应该是确定高度的足够信息。

Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. 
    Try this: 
        (1) look at each constraint and try to figure out which you don't expect; 
        (2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x7b6730c0 UIImageView:0x80eda630.height == 1.02133*UIImageView:0x80eda630.width + 1>",
    "<NSLayoutConstraint:0x7b673020 H:|-(0)-[UIImageView:0x80eda630]   (Names: '|':UITableViewCellContentView:0x80e1a590 )>",
    "<NSLayoutConstraint:0x80ee3ca0 H:[UIImageView:0x80eda630]-(0)-|   (Names: '|':UITableViewCellContentView:0x80e1a590 )>",
    "<NSLayoutConstraint:0x80ee3cd0 V:|-(0)-[UIImageView:0x80eda630]   (Names: '|':UITableViewCellContentView:0x80e1a590 )>",
    "<NSLayoutConstraint:0x80ee3d00 V:[UIImageView:0x80eda630]-(0)-|   (Names: '|':UITableViewCellContentView:0x80e1a590 )>",
    "<NSLayoutConstraint:0x80ed8760 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x80e1a590(328)]>",
    "<NSLayoutConstraint:0x80ed8730 'UIView-Encapsulated-Layout-Width' H:[UITableViewCellContentView:0x80e1a590(320)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x7b6730c0 UIImageView:0x80eda630.height == 1.02133*UIImageView:0x80eda630.width + 1>

查看imageview高度，宽度关系约束失败的约束。

但为什么呢？ 328（身高）== 1.02133 * 320（宽度）+1
1.02133 * 320（宽度）+1 =＆gt; 327.8256
对于非视网膜，它应该舍入到最近的像素，对于视网膜显示，它应该到最接近的.5像素。

感知iPhone 6的上述作品，但iPhone 5和iPhone 5s都失败了它似乎与视网膜和非视网膜无关。而且无论327.8256应该转到328。

让我明确一下解决这个问题的方法（添加明确的宽度和高度约束）。我不是在寻找一种解决方法，而是试图了解造成这种行为的原因。

使用UITableViewAutomaticDimension设置行高的UITableViewCell中的NSLayoutConstraint冲突

0 个答案: