为啥 UIBarButtonItem 图像总是模糊/模糊/像素化

Posted 2023-03-13

【中文标题】为啥 UIBarButtonItem 图像总是模糊/模糊/像素化

【英文标题】：Why is UIBarButtonItem image always fuzzy/blurry/pixelated为什么 UIBarButtonItem 图像总是模糊/模糊/像素化

【发布时间】：2014-09-15 17:37:19

【问题描述】：

这是我当前的代码：

var reply = UIBarButtonItem(image: UIImage(named: "reply"), style: UIBarButtonItemStyle.Plain, target: self, action: Selector("reply:"))
self.navigationItem.rightBarButtonItem = reply

右上角的按钮总是模糊的。这是 iPhone4s 设备的屏幕截图，因此与视网膜无关。

我尝试了从 30x30 到 512x512 的不同图像尺寸，并使用 customView 添加图像。这些方法都没有解决问题。

提前致谢。

【参考方案1】：

我已经用这个方法解决了：

var replyBtn = UIButton(frame: CGRect(x: 0, y: 0, width: 30, height: 30))
replyBtn.setImage(UIImage(named: "reply"), forState: UIControlState.Normal)
replyBtn.addTarget(self.navigationController, action: Selector("reply:"), forControlEvents:  UIControlEvents.TouchUpInside)
var item = UIBarButtonItem(customView: replyBtn)
self.navigationItem.rightBarButtonItem = item

它使用完全相同的图像显示一个非常清晰的按钮。

【讨论】：

如果不适用于 Swift 2 和 xCode 6.4 替换最后一行 //self.navigationItem.rightBarButtonItem = item 与 self.navigationController?.navigationBar.topItem?.rightBarButtonItem = item

【参考方案2】：

根据 ios 人机界面指南，图标应为 22x22 看看这里的文档： https://developer.apple.com/library/ios/documentation/UserExperience/Conceptual/MobileHIG/BarIcons.html

【参考方案3】：

试试这个：

func createBarButton(image: String, size: CGSize, offset: (x: CGFloat, y: CGFloat) = (0,0), hightlightable: Bool = true, action: Selector) -> UIBarButtonItem 
    let btn = UIButton(type: .custom)
    let img = UIImage(named: image)

    btn.setBackgroundImage(img, for: .normal)
    btn.addTarget(self, action: action, for: .touchUpInside)
    btn.frame = CGRect(x: offset.x, y: offset.y, width: size.width, height: size.height)
    btn.adjustsImageWhenHighlighted = hightlightable
    let view = UIView(frame: CGRect(x: 0, y: 0, width: size.width, height: size.height))
//        view.bounds = view.bounds.offsetBy(dx: offset.x, dy: offset.y)
    view.addSubview(btn)
    let barButton = UIBarButtonItem(customView: view)

    return barButton


self.navigationItem.rightBarButtonItem = createBarButton(image: "YOUR_IMAGE",
     size: CGSize(width: 35, height: 35),
     offset: (x: -10, y: 0),
     action: #selector(showXY))