个人在写项目中常常用到的一些代码片段，会不断更新

// 获取屏幕宽度

func deviceWidth() -> (CGFloat) {

    let width = UIScreen.mainScreen().bounds.size.width

    return width

}

// 获取屏幕高度

func deviceHeight() -> (CGFloat) {

    let height = UIScreen.mainScreen().bounds.size.height

    return height

}

// viewController添加到另一个viewController

 func addChildVC(viewController: UIViewController) {

        self.addChildViewController(viewController)

        self.view.addSubview(viewController.view)

        viewController.didMoveToParentViewController(self)

 }

// viewController从另一个viewController移除

 func removeChildVC(viewController: UIViewController){

        viewController.view.removeFromSuperview()

        viewController.willMoveToParentViewController(nil)

        viewController.removeFromParentViewController()

  }

// block常用的弱指针

weak var weakSelf = self

guard let _weakSelf = weakSelf else{return}

// 获取文字的size 

extension String{

    func qb_stringSize(font: UIFont, maxWidth: CGFloat, maxHeight: CGFloat) -> CGSize{

        let arrt: Dictionary<String, UIFont> = [NSFontAttributeName: font]

        let maxSize: CGSize = CGSize(width: maxWidth, height: maxHeight)

        let options: NSStringDrawingOptions = [.TruncatesLastVisibleLine,.UsesLineFragmentOrigin,.UsesFontLeading]

        return self.boundingRectWithSize(maxSize, options: options, attributes: arrt, context: nil).size

    }

    func qb_stringSizeWithFont(font: UIFont) -> CGSize{

        return qb_stringSize(font, maxWidth: 0, maxHeight: 0)

    }

}