Swift Development: Nslayoutconstraint Pure code for automatic layout-introductory article

Requires A view with a width of 200, through code, so that the view is 20 margins from the lower-right corner of the parent control

/* Constraint settings , the control internal constraints are added by themselves, such as the width of the height, if the other

Control constraint Then there is a parent control to add

* Create constraint nslayoutconstraint parameter description:

* Item yourself

* Attribute

* Relatedby greater than or equal to or equal to

* Toitem Another control

* Attribute Another control's familiarity

* Multiplier multiplied by how much

* Constant: plus how much

* Nslayoutconstraint: property value of one control equals property value of another control

Multiplied by how many plus how much

* Add constraint addconstraint

*/

Swift code:

Let Blueview =UIView ();

Blueview. backgroundcolor =uicolor. Bluecolor ()

self. View. Addsubview(Blueview)// system will default to autoresizing constraints

Shutdown autoresizing do not close or the program crashes

Blueview.translatesautoresizingmaskintoconstraints =false

// width constraint

Let width:nslayoutconstraint =nslayoutconstraint (Item:blueview, attribute: nslayoutattribute. Width, Relatedby:nslayoutrelation. Equal, Toitem:nil, attribute: nslayoutattribute. Notanattribute, multiplier:0.0, constant:

Blueview. addconstraint (width)// Add constraint yourself

// height constraints

Let height:nslayoutconstraint =nslayoutconstraint (Item:blueview, attribute: nslayoutattribute. Height, Relatedby:nslayoutrelation. Equal, Toitem:nil, attribute: nslayoutattribute. Notanattribute, multiplier:0.0, constant:

Blueview. addconstraint (height)// Add constraint yourself

// right constraint

Let right :nslayoutconstraint =nslayoutconstraint (Item:blueview, attribute: nslayoutattribute. Right, Relatedby:nslayoutrelation. Equal, Toitem: Self. View, attribute:nslayoutattribute. Right, multiplier:1.0, constant:--)

Blueview. superview!. AddConstraint (right)// parent control Add constraint

// bottom constraint

Let bottom:nslayoutconstraint =nslayoutconstraint (Item:blueview, attribute: nslayoutattribute. Bottom, Relatedby:nslayoutrelation. Equal, Toitem: Self. View, attribute:nslayoutattribute. Bottom, Multiplier:1.0, constant:--)

Blueview. superview!. addconstraint (bottom)// parent control Add constraint

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Swift Development: Nslayoutconstraint Pure code for automatic layout-introductory article