ios 在 Swift 3 上运行后台线程
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Run a background thread on Swift 3
提问by FS.O6
I have a function that goes like this:
我有一个像这样的函数：
fileprivate func setupImageViewWithURL(url: URL) {
var image: UIImage? = nil
do {
try image = UIImage(data: Data(contentsOf: url))!
} catch is NSError {
print("Failed")
}
image = self.imageWithImage(sourceImage: image!, scaledToWidth: UIScreen.main.bounds.size.width)
self.imageImageView.image = image
self.imageImageView.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: (image?.size.height)!)
}
I want to run it on a Backgroundthread.
我想在Backgroundthread.
I've tried the GDCmethods of Swift2, but it didn't work.
我尝试了 的GDC方法Swift2，但没有奏效。
Did anything change in the thread topic in Swift3?
中的线程主题有什么变化Swift3吗？
Thank you!
谢谢！
回答by Max Pevsner
It's OK to load image on the background, but it's not OK to perform UI updates on background thread. That's why the function must contain two threads.
在后台加载图像是可以的，但在后台线程上执行 UI 更新是不行的。这就是函数必须包含两个线程的原因。
func setupImageViewWithURL(url: URL) {
var image: UIImage? = nil
DispatchQueue.global().async {
do {
try image = UIImage(data: Data(contentsOf: url))!
} catch {
print("Failed")
}
DispatchQueue.main.async(execute: {
if image != nil {
image = self.imageWithImage(sourceImage: image!, scaledToWidth: UIScreen.main.bounds.size.width)
self.imageImageView.image = image
self.imageImageView.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: (image?.size.height)!)
}
})
}
}
回答by Prateek kumar
Swift 4.0
斯威夫特 4.0
func setupImageViewWithURL(url: URL) { var image: UIImage? = nil DispatchQueue.global(qos: .background).async { do { try image = UIImage(data: Data(contentsOf: url))! } catch { print("Failed") } DispatchQueue.main.async { if image != nil { image = self.imageWithImage(sourceImage: image!, scaledToWidth: UIScreen.main.bounds.size.width) self.imageImageView.image = image self.imageImageView.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: (image?.size.height)!) } } } }
func setupImageViewWithURL(url: URL) { var image: UIImage? = nil DispatchQueue.global(qos: .background).async { do { try image = UIImage(data: Data(contentsOf: url))! } catch { print("Failed") } DispatchQueue.main.async { if image != nil { image = self.imageWithImage(sourceImage: image!, scaledToWidth: UIScreen.main.bounds.size.width) self.imageImageView.image = image self.imageImageView.frame = CGRect(x: 0, y: 0, width: UIScreen.main.bounds.size.width, height: (image?.size.height)!) } } } }
回答by Aditya Sharma
DispatchQueue.global(qos: .background).async {
}
DispatchQueue.global(qos: .background).async {
}
