UILabel自动布局右下角限制不起作用

Question

let lbl = UILabel()
lbl.textColor = UIColor.RGB(0x74, g: 0x75, b: 0x75)
lbl.text = "180/180"
lbl.sizeToFit()
self.addSubview(lbl)
self.charsLimitLbl = lbl
lbl.translatesAutoresizingMaskIntoConstraints = false

let rightConstraints = NSLayoutConstraint.constraints(withVisualFormat: "H:[item]-padding-|", 
                                                 options: NSLayoutFormatOptions(rawValue: 0), 
                                                 metrics: ["padding" : padding], 
                                                 views: ["item" : lbl])
self.addConstraints(rightVonstraints)
let bottomConstraints = NSLayoutConstraint.constraints(withVisualFormat: "V:[item]-padding-|", 
                                                       options: NSLayoutFormatOptions(rawValue: 0),
                                                       metrics: ["padding" : padding], 
                                                       views: ["item" : lbl])

self.addConstraints(bottomConstraints)
lbl.setContentHuggingPriority(UILayoutPriorityRequired, for: .horizontal)

我将此标签添加为UITextView的子视图，由于某种原因，我的标签产生了负面原因：

  

App.WPPUILabel：0x7f9132209830; baseClass = UILabel; frame =（ -39.5   -14.5; 39.5 14.5）; text =＆＃39; 54/180＆＃39 ;; userInteractionEnabled = NO; layer = _UILabelLayer：0x63800009ddd0

我可以随时随地调用这些功能：

self.layoutIfNeeded()
self.layoutSubviews()
self.setNeedsLayout()