Question

我正在尝试学习视觉格式语言，在这种情况下，我希望视图顶部的两个按钮彼此相邻。

这是我的代码但没有出现？

UIButton *button1 = [[UIButton alloc] init];
[button1 setBackgroundColor:[UIColor blueColor]];
UIButton *button2 = [[UIButton alloc] init];
[button2 setBackgroundColor:[UIColor redColor]];
NSDictionary *views = NSDictionaryOfVariableBindings(button1, button2);
NSLog(@"%@", [views allKeys]);
NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"[button1(==button2)]" options:0 metrics:Nil views:views];
[self.view addSubview:button1];
[self.view addSubview:button2];
[self.view addConstraints:constraints];

感谢答案，现在是我的代码：

UIButton *button1 = [UIButton buttonWithType:UIButtonTypeSystem];
button1.translatesAutoresizingMaskIntoConstraints = NO;
[button1 setTitle:@"Button" forState:UIControlStateNormal];
[button1 setBackgroundColor:[UIColor redColor]];
[self.view addSubview:button1];

UIButton *button2 = [UIButton buttonWithType:UIButtonTypeSystem];
button2.translatesAutoresizingMaskIntoConstraints = NO;
[button2 setTitle:@"Button" forState:UIControlStateNormal];
[button2 setBackgroundColor:[UIColor blueColor]];
[self.view addSubview:button2];

NSDictionary *views = NSDictionaryOfVariableBindings(button1, button2);
NSString *const kHConstraint = @"|-[button1(==button2)]-[button2]-|";
NSString *const kVConstraint = @"V:|-[button1(==44)]";
NSString *const kVConstraint2 = @"V:|-[button2(==44)]";
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:kHConstraint options:0 metrics:nil views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:kVConstraint options:0 metrics:nil views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:kVConstraint2 options:0 metrics:nil views:views]];

如果我可以将两个垂直约束合并为一个，我会徘徊吗？

是的，可以使用选项NSLayoutFormatAlignAllTop：

NSDictionary *views = NSDictionaryOfVariableBindings(button1, button2);
NSString *const kHConstraint = @"H:|-[button1(==button2)]-[button2]-|";
NSString *const kVConstraint = @"V:|-[button1(==button2)]";
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:kHConstraint options:NSLayoutFormatAlignAllTop metrics:metrics views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:kVConstraint options:0 metrics:metrics views:views]];

来自：@jrturton的精彩文章，可以找到here

Answer 1

您需要为两个按钮关闭自动调整功能：

button1.translatesAutoresizingMaskIntoConstraints = NO;
button2.translatesAutoresizingMaskIntoConstraints = NO;

您必须为系统指定足够的约束，以确定每个子视图的高度，宽度和位置。否则默认帧为CGRectZero，它将不可见。
目前，您的VFL字符串将button1的宽度设置为与button2相等，但如果两个按钮的大小均为零，则仍然满足约束条件。
您的约束没有定位信息。

至少，我建议以下VFL语句为您提供所需的布局：

@"V:|-[button1(==44)]"

这使你的button1高度为44，并将其从superview顶部定位为标准插入。

@"V:|[button2(==44)]"

这与按钮2的作用相同。您也可以通过水平布局中的对齐选项来实现此目的，但这会使问题混淆。

@"|-[button1(==button2)]-[button2]-|"

这使得按钮的宽度相等，并且还将它们与superview的边缘相连。

我已经写了很长篇here的VFL，希望能帮助你理解。

iOS VFL相互显示两个按钮

1 个答案: