我一直在思考你的问题，这是我的结果，你需要子类化UILabel，在init中你需要设置userInteractionEnabled = true，然后覆盖override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?)这个方法，我的代码是这样的：

Swift 3.1代码

import UIKit

class draggableLabel: UILabel {

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.layer.borderWidth = 1
        self.layer.borderColor = UIColor.red.cgColor
        self.isUserInteractionEnabled = true
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        let touch = touches.first;
        let location = touch?.location(in: self.superview);
        if(location != nil)
        {
        self.frame.origin = CGPoint(x: location!.x-self.frame.size.width/2, y: location!.y-self.frame.size.height/2);
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {

    }

}

Swift 2.2代码

import UIKit

class draggableLabel: UILabel {

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        self.layer.borderWidth = 1
        self.layer.borderColor = UIColor.redColor().CGColor
        self.userInteractionEnabled = true
    }

    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
        let touch = touches.first;
        let location = touch?.locationInView(self.superview);
        if(location != nil)
        {
        self.frame.origin = CGPointMake(location!.x-self.frame.size.width/2, location!.y-self.frame.size.height/2);
        }
    }

    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {

    }

}

希望这对你有帮助，对我来说效果很好，这就是它的工作原理