自动布局让我的生活很困难。从理论上讲，当我转换的时候，它会非常有用，但我似乎一直在与它作斗争。
我做了一个演示项目来寻求帮助。有人知道如何使视图之间的空间增加或减少均匀，每当视图调整大小?
下面是三个标签(手动垂直对齐):
我想要的是，当我旋转时，它们均匀地调整间距(而不是视图大小)。默认情况下，顶部和底部视图向中心挤压:
当前回答
Here is a solution that will vertically center any number of subviews, even if they have unique sizes. What you want to do is make a mid-level container, center that in the superview, then put all the subviews in the container and arrange them with respect to one another. But crucially you also need to constrain them to the top and bottom of the container, so the container can be correctly sized and centered in the superview. By figuring the correct height from its subviews, the container can be vertically centered.
在本例中，self是位于所有子视图居中的父视图。
NSArray *subviews = @[ (your subviews in top-to-bottom order) ];
UIView *container = [[UIView alloc] initWithFrame:CGRectZero];
container.translatesAutoresizingMaskIntoConstraints = NO;
for (UIView *subview in subviews) {
subview.translatesAutoresizingMaskIntoConstraints = NO;
[container addSubview:subview];
}
[self addSubview:container];
[self addConstraint:[NSLayoutConstraint constraintWithItem:container attribute:NSLayoutAttributeLeft relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeLeft multiplier:1.0f constant:0.0f]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:container attribute:NSLayoutAttributeRight relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeRight multiplier:1.0f constant:0.0f]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:container attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual
toItem:self attribute:NSLayoutAttributeCenterY multiplier:1.0f constant:0.0f]];
if (0 < subviews.count) {
UIView *firstSubview = subviews[0];
[container addConstraint:[NSLayoutConstraint constraintWithItem:firstSubview attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual
toItem:container attribute:NSLayoutAttributeTop multiplier:1.0f constant:0.0f]];
UIView *lastSubview = subviews.lastObject;
[container addConstraint:[NSLayoutConstraint constraintWithItem:lastSubview attribute:NSLayoutAttributeBottom relatedBy:NSLayoutRelationEqual
toItem:container attribute:NSLayoutAttributeBottom multiplier:1.0f constant:0.0f]];
UIView *subviewAbove = nil;
for (UIView *subview in subviews) {
[container addConstraint:[NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual
toItem:container attribute:NSLayoutAttributeCenterX multiplier:1.0f constant:0.0f]];
if (subviewAbove) {
[container addConstraint:[NSLayoutConstraint constraintWithItem:subview attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual
toItem:subviewAbove attribute:NSLayoutAttributeBottom multiplier:1.0f constant:10.0f]];
}
subviewAbove = subview;
}
}
其他回答
迟到的派对，但我有一个工作的解决方案，创建一个菜单水平间距。在NSLayoutConstraint中使用==可以很容易地做到这一点
const float MENU_HEIGHT = 40;
- (UIView*) createMenuWithLabels: (NSArray *) labels
// labels is NSArray of NSString
UIView * backgroundView = [[UIView alloc]init];
backgroundView.translatesAutoresizingMaskIntoConstraints = false;
NSMutableDictionary * views = [[NSMutableDictionary alloc] init];
NSMutableString * format = [[NSMutableString alloc] initWithString: @"H:|"];
NSString * firstLabelKey;
for(NSString * str in labels)
{
UILabel * label = [[UILabel alloc] init];
label.translatesAutoresizingMaskIntoConstraints = false;
label.text = str;
label.textAlignment = NSTextAlignmentCenter;
label.textColor = [UIColor whiteColor];
[backgroundView addSubview: label];
[label fixHeightToTopBounds: MENU_HEIGHT-2];
[backgroundView addConstraints: [label fixHeightToTopBounds: MENU_HEIGHT]];
NSString * key = [self camelCaseFromString: str];
[views setObject: label forKey: key];
if(firstLabelKey == nil)
{
[format appendString: [NSString stringWithFormat: @"[%@]", key]];
firstLabelKey = key;
}
else
{
[format appendString: [NSString stringWithFormat: @"[%@(==%@)]", key, firstLabelKey]];
}
}
[format appendString: @"|"];
NSArray * constraints = [NSLayoutConstraint constraintsWithVisualFormat: (NSString *) format
options: 0
metrics: nil
views: (NSDictionary *) views];
[backgroundView addConstraints: constraints];
return backgroundView;
}
我一直在坐过山车，爱自动布局和讨厌它。喜欢它的关键似乎是接受以下几点:
接口构建器的编辑和“有帮助的”自动创建约束在大多数情况下几乎无用 创建类别来简化常见操作是一种拯救，因为代码是如此重复和冗长。
也就是说，你正在尝试的不是直接的，在接口构建器中很难实现。这在代码中很简单。这段代码，在viewDidLoad，创建和定位三个标签，你需要他们:
// Create three labels, turning off the default constraints applied to views created in code
UILabel *label1 = [UILabel new];
label1.translatesAutoresizingMaskIntoConstraints = NO;
label1.text = @"Label 1";
UILabel *label2 = [UILabel new];
label2.translatesAutoresizingMaskIntoConstraints = NO;
label2.text = @"Label 2";
UILabel *label3 = [UILabel new];
label3.translatesAutoresizingMaskIntoConstraints = NO;
label3.text = @"Label 3";
// Add them all to the view
[self.view addSubview:label1];
[self.view addSubview:label2];
[self.view addSubview:label3];
// Center them all horizontally
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:label1 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:label2 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0]];
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:label3 attribute:NSLayoutAttributeCenterX relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterX multiplier:1.0 constant:0]];
// Center the middle one vertically
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:label2 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.view attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0]];
// Position the top one half way up
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:label1 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:label2 attribute:NSLayoutAttributeCenterY multiplier:0.5 constant:0]];
// Position the bottom one half way down
[self.view addConstraint:[NSLayoutConstraint constraintWithItem:label3 attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:label2 attribute:NSLayoutAttributeCenterY multiplier:1.5 constant:0]];
我说过，这段代码通过UIView中的一些类别方法简化了很多，但为了清晰起见，这里我做了很多。
对于感兴趣的人来说，这个类别在这里，它有一个方法，可以沿着特定的轴均匀地间隔一个视图数组。
我知道距离第一个答案已经有一段时间了，但我刚刚遇到了同样的问题，我想分享我的解决方案。为了子孙后代……
我在viewDidLoad上设置了视图:
- (void)viewDidLoad {
[super viewDidLoad];
cancelButton = [UIButton buttonWithType: UIButtonTypeRoundedRect];
cancelButton.translatesAutoresizingMaskIntoConstraints = NO;
[cancelButton setTitle:@"Cancel" forState:UIControlStateNormal];
[self.view addSubview:cancelButton];
middleButton = [UIButton buttonWithType: UIButtonTypeRoundedRect];
middleButton.translatesAutoresizingMaskIntoConstraints = NO;
[middleButton setTitle:@"Middle" forState:UIControlStateNormal];
[self.view addSubview:middleButton];
nextButton = [UIButton buttonWithType: UIButtonTypeRoundedRect];
nextButton.translatesAutoresizingMaskIntoConstraints = NO;
[nextButton setTitle:@"Next" forState:UIControlStateNormal];
[self.view addSubview:nextButton];
[self.view setNeedsUpdateConstraints];
}
然后，在updateViewConstrains上，首先删除所有约束，然后创建视图字典，然后计算视图之间使用的空间。在那之后，我只是使用视觉语言格式设置约束:
- (void)updateViewConstraints {
[super updateViewConstraints];
[self.view removeConstraints:self.view.constraints];
NSDictionary *viewsDictionary = NSDictionaryOfVariableBindings(cancelButton, nextButton, middleButton);
float distance=(self.view.bounds.size.width-cancelButton.intrinsicContentSize.width-nextButton.intrinsicContentSize.width-middleButton.intrinsicContentSize.width-20-20)/ ([viewsDictionary count]-1); // 2 times 20 counts for the left & rigth margins
NSNumber *distancies=[NSNumber numberWithFloat:distance];
// NSLog(@"Distancies: %@", distancies);
//
// NSLog(@"View Width: %f", self.view.bounds.size.width);
// NSLog(@"Cancel Width: %f", cancelButton.intrinsicContentSize.width);
// NSLog(@"Middle Width: %f", middleButton.intrinsicContentSize.width);
// NSLog(@"Next Width: %f", nextButton.intrinsicContentSize.width);
NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"|-[cancelButton]-dis-[middleButton]-dis-[nextButton]-|"
options:NSLayoutFormatAlignAllBaseline
metrics:@{@"dis":distancies}
views:viewsDictionary];
[self.view addConstraints:constraints];
constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:[nextButton]-|"
options:0
metrics:nil
views:viewsDictionary];
[self.view addConstraints:constraints];
}
这种方法的好处是你只需要做很少的数学运算。我并不是说这是完美的解决方案，但我为我试图实现的布局工作。
我希望这能有所帮助。
基于Ben Dolman的回答，这将更均匀地分配视图(使用填充等):
+(NSArray *)constraintsForEvenDistributionOfItems:(NSArray *)views
relativeToCenterOfItem:(id)toView vertically:(BOOL)vertically
{
NSMutableArray *constraints = [NSMutableArray new];
NSLayoutAttribute attr = vertically ? NSLayoutAttributeCenterY : NSLayoutAttributeCenterX;
CGFloat min = 0.25;
CGFloat max = 1.75;
CGFloat d = (max-min) / ([views count] - 1);
for (NSUInteger i = 0; i < [views count]; i++) {
id view = views[i];
CGFloat multiplier = i * d + min;
NSLayoutConstraint *constraint = [NSLayoutConstraint constraintWithItem:view
attribute:attr
relatedBy:NSLayoutRelationEqual
toItem:toView
attribute:attr
multiplier:multiplier
constant:0];
[constraints addObject:constraint];
}
return constraints;
}
对于标签，这至少是可行的:
@“H: | -15 -(第一(第二)= =]-[二(= =第三)](第三(= =))-15 - |
如果第一个和第二个有相同的宽度，第二个和第三个有相同的宽度，第三个和第一个有相同的宽度……你可以做水平(H)和垂直(V)。
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