swift 第四课

项目中经常遇到按钮改变文字和图片位置的情况，所以尝试写一个 button 的分类

import Foundation
import UIKit
/*枚举 设置 图片的位置*/
enum ButtonImagePosition : Int{

    case PositionTop = 0
    case Positionleft
    case PositionBottom
    case PositionRight
}

extension UIButton {/**imageName:图片的名字title：button 的名字type ：image 的位置 Space ：图片文字之间的间距    */
    func setImageAndTitle(imageName:String,title:String,type:ButtonImagePosition,Space space:CGFloat)  {

        self.setTitle(title, for: .normal)
        self.setImage(UIImage(named:imageName), for: .normal)

        let imageWith :CGFloat = (self.imageView?.frame.size.width)!;
        let imageHeight :CGFloat = (self.imageView?.frame.size.height)!;

        var labelWidth :CGFloat = 0.0;
        var labelHeight :CGFloat = 0.0;

        labelWidth = CGFloat(self.titleLabel!.intrinsicContentSize.width);
        labelHeight = CGFloat(self.titleLabel!.intrinsicContentSize.height);
        var  imageEdgeInsets :UIEdgeInsets = UIEdgeInsets();
        var  labelEdgeInsets :UIEdgeInsets = UIEdgeInsets();

        switch type {
        case .PositionTop:
                imageEdgeInsets = UIEdgeInsetsMake(-labelHeight - space/2.0, 0, 0, -labelWidth);
                labelEdgeInsets = UIEdgeInsetsMake(0, -imageWith, -imageHeight-space/2.0, 0);
            break;
        case .Positionleft:
                imageEdgeInsets = UIEdgeInsetsMake(0, -space/2.0, 0, space/2.0);
                labelEdgeInsets = UIEdgeInsetsMake(0, space/2.0, 0, -space/2.0);
            break;
        case .PositionBottom:
                imageEdgeInsets = UIEdgeInsetsMake(0, 0, -labelHeight-space/2.0, -labelWidth);
                labelEdgeInsets = UIEdgeInsetsMake(-imageHeight-space/2.0, -imageWith, 0, 0);
            break;
        case .PositionRight:
                imageEdgeInsets = UIEdgeInsetsMake(0, labelWidth+space/2.0, 0, -labelWidth-space/2.0);
                labelEdgeInsets = UIEdgeInsetsMake(0, -imageWith-space/2.0, 0, imageWith+space/2.0);
            break;
        }

        // 4. 赋值
        self.titleEdgeInsets = labelEdgeInsets;
        self.imageEdgeInsets = imageEdgeInsets;
    }
}