swift – 带图标和文本的UITableViewRowAction

第一部分是标准委托方法：

func tableView(_ tableView: UITableView,editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {

    let stockWidth = String(repeating: " ",count: 8)
    let rename = UITableViewRowAction(style: .normal,title: stockWidth) { (_,indexPath) in
        self.renameEntry(indexPath)
    }
    self.fixAction(rename,text: "Rename",image: UIImage(named: "pencilEdit")!,color: UIColor(52,61,70))
    let locate = UITableViewRowAction(style: .normal,indexPath) in
        self.locateEntry(indexPath)
    }
    self.fixAction(locate,text: "Locate",image: UIImage(named: "locatePin")!,color: UIColor(38,107,215))
    let delete = UITableViewRowAction(style: .normal,indexPath) in
        self.deleteEntry(indexPath)
    }
    self.fixAction(delete,text: "Forget",image: UIImage(named: "triggerDeleteSelector")!,color: UIColor(227,34,60))
    let gap = UITableViewRowAction(style: .normal,title: "") { (_,_) in
        // pass
    }
    gap.backgroundColor = UIColor.clear
    return [gap,delete,rename]
}

那里有两个不明显的细节.首先,动作从传入的文本字符串中获取其宽度.如果您没有通过一些不可见的空格字符给它一些宽度,则背景图像将不会有任何区域被绘制.这就是为什么前3个操作中使用的stockWidth字符串.它的8个字符宽度由生成背景图像的fixAction方法共享.

第二个细节是在底部包含第四个“间隙”动作.出于某种原因,如果第一个动作具有作为平铺图案的背景颜色,则它将在其他动作下向左伸展.我发现我必须在前面插入这个零宽度没有操作以避免这种情况.

func fixAction(_ action:UITableViewRowAction,text:String,image:UIImage,color:UIColor) {
    // make sure the image is a mask that we can color with the passed color
    let mask = image.withRenderingMode(.alwaysTemplate) 
    // compute the anticipated width of that non empty string
    let stockSize = action.title!.sizeWithAttributes([NSFontAttributeName: UIFont.systemFont(ofSize: 18)])
    // I know my row height
    let height:CGFloat = 70
    // Standard action width computation seems to add 15px on either side of the text
    let width = (stockSize.width + 30).ceiling 
    let actionSize = CGSize(width: width,height: height)
    // lets draw an image of actionSize
    UIGraphicsBeginImageContextWithOptions(actionSize,false,0.0)
    if let context = UIGraphicsGetCurrentContext() {
        context.clear(CGRect(origin: .zero,size: actionSize))
    }
    color.set()
    let attributes = [NSForegroundColorAttributeName: color,NSFontAttributeName: UIFont(name: "Avenir-Book",size: 13)]
    let textSize = text.size(attributes: attributes)
    // implementation of `half` extension left up to the student
    let textPoint = CGPoint(x: (width - textSize.width).half,y: (height - (textSize.height * 3)).half + (textSize.height * 2))
    text.draw(at: textPoint,withAttributes: attributes)
    let  maskHeight = textSize.height * 2
    let maskRect = CGRect(x: (width - maskHeight).half,y: textPoint.y - maskHeight,width: maskHeight,height: maskHeight)
    mask.draw(in: maskRect)
    if let result = UIGraphicsGetImageFromCurrentImageContext() {
        // adjust the passed in action's backgroundColor to a patternImage
        action.backgroundColor = UIColor(patternImage: result)
    }
    else {
        "WTH!!!".logError()
    }
    UIGraphicsEndImageContext()
}