代碼見下方
//不自動轉(zhuǎn)換為constrains
//歷史原因造成的
?//得設(shè)成false后下面添加的約誰才能生效
subView.translatesAutoresizingMaskIntoConstraints =false
//添加視圖進(jìn)去
view.addSubview(subView)
//創(chuàng)建三條約束
letsc1 = NSLayoutConstraint(
item: subView,
attribute: NSLayoutAttribute.Top,
relatedBy: NSLayoutRelation.Equal,
toItem: topLayoutGuide,
attribute: NSLayoutAttribute.Bottom,
multiplier:1,
constant:0
)
letsc2 = NSLayoutConstraint(
item: subView,
attribute: NSLayoutAttribute.Leading,
relatedBy: NSLayoutRelation.Equal,
toItem: subView.superview,
attribute: NSLayoutAttribute.Leading,
multiplier:1,
constant:0
)
letsc3 = NSLayoutConstraint(
item: subView,
attribute: NSLayoutAttribute.Trailing,
relatedBy: NSLayoutRelation.Equal,
toItem: subView.superview,
attribute: NSLayoutAttribute.Trailing,
multiplier:1,
constant:0
)
//使創(chuàng)建的約束生效
NSLayoutConstraint.activateConstraints([sc1,sc2,sc3])
