Ios 间距填充在两个视图之间不起作用，是否存在视觉布局约束？

我想在field1和field2之间添加一个填充，它在情节提要中起作用，但我需要以编程方式进行设置，所以我尝试了这个方法，但这两个字段彼此相邻，这两个字段之间没有30的间距： 容器为绿色，字段1为橙色，字段2为蓝色：

    var fviews = ["field1":field1, "field2":field2, "field3":field3, "field4":field4 ]
    let metrics : [NSObject: AnyObject] = ["spacingV" : 30]

    //FIELD 2 
    fviews = [ "field1":field1, "field2":field2 ]
    str = "V:|[field1]-(==spacingV)-[field2]" //----> HERE, I also tried -spacingV-
    var verticalFields = NSLayoutConstraint.constraintsWithVisualFormat(str, options: nil, metrics: metrics, views: fviews)
    self.view.addConstraints(verticalFields)

    //equal height with multiplier 0.2 :
    equalHeightMult = NSLayoutConstraint(item: field2,
        attribute: NSLayoutAttribute.Height,
        relatedBy: NSLayoutRelation.Equal,
        toItem: container,
        attribute: NSLayoutAttribute.Height,
        multiplier: 0.2,
        constant: 0)
    self.view.addConstraint(equalHeightMult)

    //align X center
    centerXConstraint =
        NSLayoutConstraint(item: field2,
            attribute: NSLayoutAttribute.CenterX,
            relatedBy: NSLayoutRelation.Equal,
            toItem: container,
            attribute: NSLayoutAttribute.CenterX,
            multiplier: 1.0,
            constant: 0)
    self.view.addConstraint(centerXConstraint)

    //HORIZONTAL: equal width with multiplier 0.7 :
    equalWidthMult = NSLayoutConstraint(item: field2,
        attribute: NSLayoutAttribute.Width,
        relatedBy: NSLayoutRelation.Equal,
        toItem: container,
        attribute: NSLayoutAttribute.Width,
        multiplier: 0.7,
        constant: 0)
    self.view.addConstraint(equalWidthMult)

你应该改变

str = "V:|[field1]-(==spacingV)-[field2]"

到

---

我不知道为什么，但现在它工作了，两种语法，谢谢你的回答

str = "V:|[field1]-(spacingV)-[field2]"