我在一個(gè)超級(jí)視圖中創(chuàng)建了兩個(gè)視圖，然后在視圖之間添加了約束：_indicatorConstrainWidth = [NSLayoutConstraint constraintWithItem:self.view1 attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:self.view2 attribute:NSLayoutAttributeWidth multiplier:1.0f constant:0.0f];[_indicatorConstrainWidth setPriority:UILayoutPriorityDefaultLow];_indicatorConstrainHeight = [NSLayoutConstraint constraintWithItem:self.view1 attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:self.view2 attribute:NSLayoutAttributeHeight multiplier:1.0f constant:0.0f];[_indicatorConstrainHeight setPriority:UILayoutPriorityDefaultLow];[self addConstraint:_indicatorConstrainWidth];[self addConstraint:_indicatorConstrainHeight];現(xiàn)在，我想用動(dòng)畫更改乘子屬性，但是我不知道如何更改乘子屬性。（我在頭文件NSLayoutConstraint.h的私有屬性中找到了_coefficient，但它是私有的。）如何更改多重屬性？我的解決方法是刪除舊的約束，并為添加新的約束multipler。
3 回答
湖上湖
TA貢獻(xiàn)2003條經(jīng)驗(yàn) 獲得超2個(gè)贊
這是Swift中的NSLayoutConstraint擴(kuò)展，可以輕松設(shè)置新的乘數(shù)：
import UIKit
extension NSLayoutConstraint {
func setMultiplier(multiplier:CGFloat) -> NSLayoutConstraint {
NSLayoutConstraint.deactivateConstraints([self])
let newConstraint = NSLayoutConstraint(
item: firstItem,
attribute: firstAttribute,
relatedBy: relation,
toItem: secondItem,
attribute: secondAttribute,
multiplier: multiplier,
constant: constant)
newConstraint.priority = priority
newConstraint.shouldBeArchived = shouldBeArchived
newConstraint.identifier = identifier
NSLayoutConstraint.activateConstraints([newConstraint])
return newConstraint
}
}
在Swift 3.0中
import UIKit
extension NSLayoutConstraint {
/**
Change multiplier constraint
- parameter multiplier: CGFloat
- returns: NSLayoutConstraint
*/
func setMultiplier(multiplier:CGFloat) -> NSLayoutConstraint {
NSLayoutConstraint.deactivate([self])
let newConstraint = NSLayoutConstraint(
item: firstItem,
attribute: firstAttribute,
relatedBy: relation,
toItem: secondItem,
attribute: secondAttribute,
multiplier: multiplier,
constant: constant)
newConstraint.priority = priority
newConstraint.shouldBeArchived = self.shouldBeArchived
newConstraint.identifier = self.identifier
NSLayoutConstraint.activate([newConstraint])
return newConstraint
}
}
演示用法：
@IBOutlet weak var myDemoConstraint:NSLayoutConstraint!
override func viewDidLoad() {
let newMultiplier:CGFloat = 0.80
myDemoConstraint = myDemoConstraint.setMultiplier(newMultiplier)
//If later in view lifecycle, you may need to call view.layoutIfNeeded()
}
大話西游666
TA貢獻(xiàn)1817條經(jīng)驗(yàn) 獲得超14個(gè)贊
我用來更改現(xiàn)有布局約束的乘數(shù)的輔助函數(shù)。它創(chuàng)建并激活了一個(gè)新的約束，并停用了舊的約束。
struct MyConstraint {
static func changeMultiplier(_ constraint: NSLayoutConstraint, multiplier: CGFloat) -> NSLayoutConstraint {
let newConstraint = NSLayoutConstraint(
item: constraint.firstItem,
attribute: constraint.firstAttribute,
relatedBy: constraint.relation,
toItem: constraint.secondItem,
attribute: constraint.secondAttribute,
multiplier: multiplier,
constant: constraint.constant)
newConstraint.priority = constraint.priority
NSLayoutConstraint.deactivate([constraint])
NSLayoutConstraint.activate([newConstraint])
return newConstraint
}
}
用法，將乘數(shù)更改為1.2：
constraint = MyConstraint.changeMultiplier(constraint, multiplier: 1.2)
- 3 回答
- 0 關(guān)注
- 1371 瀏覽
添加回答
舉報(bào)
0/150
提交
取消