作者JGC18 (JGC)
看板MacDev
标题[问题] URLSession即便没网路还是可以拿到资料
时间Sun Sep 10 16:20:02 2017
各位前辈好, 小弟目前正在自学写ios app
功能是在viewDidLoad()去网路上面抓一张图显示到imageview这样
查到网路上的做法是用URLSession去拿资料
第一次跑起app顺利载入图片
但是当我把手机网路全部切断, 重新打开app, 居然还可以载到图片@@
response 的 data居然都有值
是不是有什麽暂存的地方存了这张图片呢?
或是该用什麽关键字去解决这样的情况, 请麻烦给我一些意见
下面是我简单的测试程式
storyboard上面只有一个ImageView
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let testAddress="
http://az616578.vo.msecnd.net/files/2016/05/02/635977562108560005-679443365_kobe.jpg"
print("Begin of code")
if let checkedUrl = URL(string: testAddress) {
image1.contentMode = .scaleAspectFit
downloadImage(url: checkedUrl)
}
print("End of code. The image will continue downloading in the background and it will be loaded when it ends.")
}
//download image
func getDataFromUrl(url: URL, completion: @escaping (_ data: Data?, _ response: URLResponse?, _ error: Error?) -> Void) {
URLSession.shared.dataTask(with: url) {
(data, response, error) in
completion(data, response, error)
}.resume()
}
func downloadImage(url: URL) {
print("Download Started")
getDataFromUrl(url: url) { (data, response, error) in
guard let data = data, error == nil else {
print("Download error=\(error)")
return
}
print(response?.suggestedFilename ?? url.lastPathComponent)
print("Download Finished")
DispatchQueue.main.async() { () -> Void in
self.image1.image = UIImage(data: data)
}
}
}
--
※ 发信站: 批踢踢实业坊(ptt.cc), 来自: 175.182.116.114
※ 文章网址: https://webptt.com/cn.aspx?n=bbs/MacDev/M.1505031605.A.DA6.html
2F：→ bbkaf: 要设定cachePolicy 09/10 18:27
3F：推 luckycan: 推楼上，学习了 09/10 20:42
4F：→ JGC18: 谢谢bbkaf,原来要设定这参数,可以了,谢谢 09/10 21:42