使用AutoLayout（>；iOS 6）对子视图进行自动和动态换行
我希望子视图在其superview内水平对齐（具有固定宽度），并在到达superview的后缘时自动“换行”。 我正在寻找一种解决方案，使Auto Layout能够在子视图的大小动态变化时（例如，文本字段随内容的增长/收缩）和添加或删除约束时，为我完成全部工作，而不必重新计算行结构 我已经有了一个（有效的）解决方案，即根据子视图的预先（和重新）计算的行结构（重新）创建约束 所以我的问题是：能否找到一种解决方案，在这样一个星座中使用约束（具有灵活性、优先级a.s.o.），使自动布局能够在需要时（在首次加载和运行时）在子视图上自动断线。 我创建了一个示例项目，其中使用AutoLayout（>；iOS 6）对子视图进行自动和动态换行,ios,autolayout,nslayoutconstraint,Ios,Autolayout,Nslayoutconstraint,我希望子视图在其superview内水平对齐（具有固定宽度），并在到达superview的后缘时自动“换行”。 我正在寻找一种解决方案，使Auto Layout能够在子视图的大小动态变化时（例如，文本字段随内容的增长/收缩）和添加或删除约束时，为我完成全部工作，而不必重新计算行结构 我已经有了一个（有效的）解决方案，即根据子视图的预先（和重新）计算的行结构（重新）创建约束 所以我的问题是：能否找到一种解决方案，在这样一个星座中使用约束（具有灵活性、优先级a.s.o.），使自动布局能够在需要时（在
UILabels- (void) addConstraintsForLabels : (NSArray*) labels
superview : (UIView*) superview {
for (int i = 0; i < labels.count; i++) {
UILabel* precedingLabel = i == 0 ? nil : labels[i - 1];
UILabel* label = labels[i];
[label setTranslatesAutoresizingMaskIntoConstraints: NO];
//// set all contentHuggingPriorities to no growing and no compression
[label setContentHuggingPriority: UILayoutPriorityRequired forAxis: UILayoutConstraintAxisHorizontal];
[label setContentHuggingPriority: UILayoutPriorityRequired forAxis: UILayoutConstraintAxisVertical];
[label setContentCompressionResistancePriority: UILayoutPriorityRequired forAxis: UILayoutConstraintAxisHorizontal];
[label setContentCompressionResistancePriority: UILayoutPriorityRequired forAxis: UILayoutConstraintAxisVertical];
//// constraints affecting superview
// top to superview
NSLayoutConstraint* topToSup = [NSLayoutConstraint alignEdge: NSLayoutAttributeTop ofViews: @[label, superview] relation: i == 0 ? NSLayoutRelationEqual : NSLayoutRelationGreaterThanOrEqual
spacing: 0];
// leading to superview
NSLayoutConstraint* leadingToSup = [NSLayoutConstraint alignEdge: NSLayoutAttributeLeading
ofViews: @[label, superview]
relation: i == 0 ? NSLayoutRelationEqual : NSLayoutRelationGreaterThanOrEqual
spacing: 0];
// bottom to superview
NSLayoutConstraint* bottomToSup = [NSLayoutConstraint alignEdge: NSLayoutAttributeBottom
ofViews: @[label, superview]
relation: i == labels.count - 1 ? NSLayoutRelationEqual : NSLayoutRelationLessThanOrEqual
spacing: 0];
// trailing to superview
NSLayoutConstraint* trailingToSup = [NSLayoutConstraint alignEdge: NSLayoutAttributeTrailing
ofViews: @[label, superview]
relation: NSLayoutRelationLessThanOrEqual
spacing: 0];
//// example constraints affecting preceding label
// leading to preceding label
NSLayoutConstraint* leadingToPrec = precedingLabel == nil ? nil : [NSLayoutConstraint horizontalSpacing: 0
betweenViews: @[precedingLabel, label]
flexible: NO
inMaximum: NO];
// y position to preceding label
NSLayoutConstraint* centerYToPrec = precedingLabel == nil ? nil : [NSLayoutConstraint alignEdge: NSLayoutAttributeCenterY
ofViews: @[label, precedingLabel]
relation: NSLayoutRelationEqual
spacing: 0];
// top to preceding view
NSLayoutConstraint* topToPrec = precedingLabel == nil ? nil : [NSLayoutConstraint verticalSpacing: 0
ofViews: @[precedingLabel, label]
flexible: NO
inMaximum: NO];
//// priorities
// affecting the superview
topToSup.priority = UILayoutPriorityRequired; // is either flexible or non-flexible for the first
leadingToSup.priority = UILayoutPriorityRequired; // is either flexible or non-flexible for the first
bottomToSup.priority = UILayoutPriorityRequired; // is either flexible or non-flexible for the last
trailingToSup.priority = UILayoutPriorityRequired; // it is required, that the view does not exceed the right edge of its superview
[superview addConstraints: @[trailingToSup, topToSup, leadingToSup, bottomToSup]];
// affecting the preceding view
if (i > 0) {
leadingToPrec.priority = UILayoutPriorityDefaultHigh;
centerYToPrec.priority = UILayoutPriorityDefaultHigh;
topToPrec.priority = UILayoutPriorityDefaultHigh;
[superview addConstraints: @[leadingToPrec, centerYToPrec, topToPrec]];
}
}
}
对于自动布局来说，这是一项非常艰巨的任务。随着添加越来越多的约束，约束的求解时间呈指数增长。看起来UICollectionView可能更适合您的需要。它已经非常适合这样做，特别是UICollectionViewFlowLayout布局。请将提供的代码缩减到包含问题的部分。你应该自己找出是什么引起了这个错误，而不是把它委托给社区！我既没有错误问题，也不知道上面的截图结果来自哪里。但无论如何，为了更清晰，我将稍微减少代码。谢谢，谢谢你的回答。因此，我关于
UICollectionViewFlowLayoutUICollectionViewUICollectionViewCellUITextFieldUICollectionViewUICollectionView@implementation NSLayoutConstraint (ConstructorAdditions)
// align edges of two views
// if one view is the superview, put it at the second position in the array
+ (NSLayoutConstraint*) alignEdge : (NSLayoutAttribute) edge
ofViews : (NSArray*) /*UIView*/ views
relation : (NSLayoutRelation) relation
spacing : (CGFloat) spacing {
NSLayoutConstraint* constraint = nil;
if (views.count == 2) {
if (edge == NSLayoutAttributeBaseline || edge == NSLayoutAttributeTrailing || edge == NSLayoutAttributeBottom || edge == NSLayoutAttributeRight) {
spacing = -spacing;
}
constraint = [NSLayoutConstraint constraintWithItem : [views objectAtIndex: 0]
attribute : edge
relatedBy : relation
toItem : [views objectAtIndex: 1]
attribute : edge
multiplier : 1.0
constant : spacing];
}
return constraint;
}
// vertical spcacing between views
// the method assumes, that the first view in the array is above the second view
+ (NSLayoutConstraint*) verticalSpacing : (CGFloat) spacing
ofViews : (NSArray*) /*UIView*/ views
flexible : (BOOL) flexible
inMaximum: (BOOL) inMax {
NSLayoutConstraint* constraint = nil;
NSLayoutRelation relation = flexible ? (inMax ? NSLayoutRelationLessThanOrEqual : NSLayoutRelationGreaterThanOrEqual) : NSLayoutRelationEqual;
if (views.count == 2) {
constraint = [NSLayoutConstraint constraintWithItem : [views objectAtIndex: 0]
attribute : NSLayoutAttributeBottom
relatedBy : relation
toItem : [views objectAtIndex: 1]
attribute : NSLayoutAttributeTop
multiplier : 1.0
constant : -spacing];
}
return constraint;
}
// horizontal spacing between views
// the method assumes, that the first view in the array is left of the second view
+ (NSLayoutConstraint*) horizontalSpacing : (CGFloat) spacing
betweenViews : (NSArray*) /*UIView*/ views
flexible : (BOOL) flexible
inMaximum: (BOOL) inMax {
NSLayoutConstraint* constraint = nil;
NSLayoutRelation relation = flexible ? (inMax ? NSLayoutRelationLessThanOrEqual : NSLayoutRelationGreaterThanOrEqual) : NSLayoutRelationEqual;
if (views.count == 2) {
constraint = [NSLayoutConstraint constraintWithItem : [views objectAtIndex: 0]
attribute : NSLayoutAttributeTrailing
relatedBy : relation
toItem : [views objectAtIndex: 1]
attribute : NSLayoutAttributeLeading
multiplier : 1.0
constant : -spacing];
}
return constraint;
}
+ (NSArray*) equalWidthOfViews : (NSArray*) views
toView : (UIView*) view
distance : (CGFloat) distance
relation : (NSLayoutRelation) relation
multiplier : (CGFloat) multiplier {
NSMutableArray* constraints = [[NSMutableArray alloc] initWithCapacity: views.count];
for (UIView* aView in views) {
[constraints addObject: [NSLayoutConstraint constraintWithItem : aView
attribute : NSLayoutAttributeWidth
relatedBy : relation
toItem : view
attribute : NSLayoutAttributeWidth
multiplier : multiplier
constant : distance]];
}
return constraints;
}