ios – 如何使用Swift保存远程图像？

概述我试图用 Swift显示和保存图像.在第一击中,它在imageview上显示远程图像,第二次按下它会显示空白的imageview,而不是应该是第一次保存的本地图像. var paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as String var image 我试图用 Swift显示和保存图像.在第一击中,它在imagevIEw上显示远程图像,第二次按下它会显示空白的imagevIEw,而不是应该是第一次保存的本地图像.

var paths = NSSearchPathForDirectorIEsInDomains(.documentDirectory,.UserDomainMask,true)[0] as String    var imagePath = paths.stringByAppendingPathComponent("images/\(ID)/logo.jpg" )    var checkImage = NSfileManager.defaultManager()    if (checkImage.fileExistsAtPath(imagePath)) {        let getimage = UIImage(contentsOffile: imagePath)        self.image?.image = getimage    } else {        dispatch_async(dispatch_get_main_queue()) {            let getimage =  UIImage(data: NSData(contentsOfURL: NSURL(string: remoteImage)))            UIImageJPEGRepresentation(getimage,100).writetofile(imagePath,atomically: true)            self.image?.image = getimage        }    }

编辑：这一个为我工作.

var paths = NSSearchPathForDirectorIEsInDomains(.documentDirectory,true)[0] as Stringvar dirPath = paths.stringByAppendingPathComponent("images/\(ID)" )var imagePath = paths.stringByAppendingPathComponent("images/\(ID)/logo.jpg" )var checkImage = NSfileManager.defaultManager()if (checkImage.fileExistsAtPath(imagePath)) {    let getimage = UIImage(contentsOffile: imagePath)    self.image?.image = getimage} else {    dispatch_async(dispatch_get_global_queue(disPATCH_QUEUE_PRIORITY_BACKGROUND,0)) {        checkImage.createDirectoryAtPath(dirPath,withIntermediateDirectorIEs: true,attributes: nil,error: nil)        let getimage =  UIImage(data: NSData(contentsOfURL: NSURL(string: remoteImage)))        UIImageJPEGRepresentation(getimage,atomically: true)        dispatch_async(dispatch_get_main_queue()) {            self.image?.image = getimage            return        }    }}

解决方法 要回答你的主要问题,你打电话给错误的UIImage初始化程序.您应该在swift 2中调用UIImage(contentsOffile：imagePath),并在swift 3中调用UIImage(contentsOf：imagePath).

另外,看起来您正在使用dispatch_async(或swift 3中的dispatchQueue)在后台进行远程抓取,但是您将其传递给主队列,因此您实际上阻止了主/ .您应该将其分派到其中一个后台队列,然后在实际在UI中设置图像时将其分派回主队列：

Swift 3：

dispatchQueue.global(qos: dispatchQoS.background.qosClass).async {    do {        let data = try Data(contentsOf: URL(string: self.remoteImage)!)        let getimage = UIImage(data: data)        try UIImageJPEGRepresentation(getimage!,100)?.write(to: imagePath)        dispatchQueue.main.async {            self.image?.image = getimage            return        }    }    catch {            return    }}

Swift 2：

dispatch_async(dispatch_get_global_queue(disPATCH_QUEUE_PRIORITY_BACKGROUND,0)) {    let getimage =  UIImage(data: NSData(contentsOfURL: NSURL(string: self.remoteImage)))    UIImageJPEGRepresentation(getimage,atomically: true)    dispatch_async(dispatch_get_main_queue()) {        self.image?.image = getimage        return    }}

@Rob’s answer re：获取远程图像并保存它真的是最好的方法.

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