cocoa - NSTextField 和自动布局 : Autogrow height -> Programmatically

Question

如果我在界面生成器中创建一个标签并通过不适合其当前大小的代码设置一个字符串，则标签将垂直增长以适合其大小，太棒了!除了 x 和 y 约束之外，Xcode 还创建一个包含拥抱和压缩阻力的 NSContentSizeLayoutConstraint。

这是约束的日志输出

<NSContentSizeLayoutConstraint:0x6080000a11a0 V:[NSTextField:0x600000180c30(17)] Hug:750 CompressionResistance:750>

问题是，如何以编程方式执行此操作？我还没有找到方法。无法创建 NSContentSizeLayoutConstraint 并且设置 NSTextField 的 contentCompressionResistance 似乎没有任何效果。

这是我的代码:

 self.label = [[NSTextField alloc]initWithFrame:NSMakeRect(0, 0, 100, 20)];
[self.label setTranslatesAutoresizingMaskIntoConstraints:NO];
[self.label setBordered:YES];
[[self.label cell] setLineBreakMode:NSLineBreakByWordWrapping];
[self.window.contentView addSubview:self.label];
 self.label.stringValue = @"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";

NSDictionary *dict = @{@"label" : self.label};
[self.label.superview addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label]"options:0 metrics:nil views:dict]];
[self.label.superview addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[label]" options:0 metrics:nil views:dict]];

NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:self.label attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:0 constant:40];
constraint.priority = 1;
[self.label addConstraint:constraint];
constraint = [NSLayoutConstraint constraintWithItem:self.label attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:nil attribute:0 multiplier:0 constant:18];
constraint.priority = 1;
[self.label addConstraint:constraint];

[self.label setContentCompressionResistancePriority:1000 forOrientation:NSLayoutConstraintOrientationHorizontal];
[self.label setContentCompressionResistancePriority:1000 forOrientation:NSLayoutConstraintOrientationVertical];

Answer 1

设置文本字段的preferredMaxLayoutWidth。我认为您不希望或不需要显式宽度约束。

<小时/>

在我的测试中，我发现这有效:

self.label = [[NSTextField alloc] initWithFrame:NSMakeRect(0, 0, 100, 18)];
self.label.translatesAutoresizingMaskIntoConstraints = NO;
[self.label.cell setLineBreakMode:NSLineBreakByWordWrapping];
self.label.stringValue = @"Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum.";
self.label.preferredMaxLayoutWidth = 100;
self.label.editable = NO;

[self.window.contentView addSubview:self.label];

NSDictionary* views = @{ @"label" : self.label };
[self.label.superview addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-[label]" options:0 metrics:nil views:views]];
[self.label.superview addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-[label]" options:0 metrics:nil views:views]];

基本上，与您的主要区别在于我将editable设置为NO。我还省略了宽度和高度限制并设置压缩阻力。