自动调整UITableViewCell内容的大小

UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleHeight

NSLayoutConstraint.activate([
    // 指定UIView的左边距和右边距
    self.addConstraint(NSLayoutConstraint(item: self, attribute: .left, relatedBy: .equal, toItem: self.superview, attribute: .left, multiplier: 1, constant: 0)),
    self.addConstraint(NSLayoutConstraint(item: self, attribute: .right, relatedBy: .equal, toItem: self.superview, attribute: .right, multiplier: 1, constant: 0)),
    // 指定UIView的下边距和上边距
    self.addConstraint(NSLayoutConstraint(item: self, attribute: .bottom, relatedBy: .equal, toItem: self.superview, attribute: .bottom, multiplier: 1, constant: 0)),
    self.addConstraint(NSLayoutConstraint(item: self, attribute: .top, relatedBy: .equal, toItem: self.superview, attribute: .top, multiplier: 1, constant: 0))
])

self.contentView.frame = CGRect(x: 0, y: 0, width: self.bounds.width, height: self.bounds.height)