我已经创建了一个图片库，我已经完成了所有使用低分辨率图像的工作，因为据我所知，如果你使用过多的高分辨率，它会崩溃我的应用程序。我现在面临的问题是，当用户点击图片时，在刷了9-10张图片后，它会崩溃应用程序。阻止这种情况发生的最佳做法是什么？
这是我的加载页面功能，我相信这个问题可能是：
func loadPage(page: Int) {
if page < 0 || page >= arrGallery.count {
// If it's outside the range of what you have to display, then do nothing
return
}
if let page = pageViews[page] {
// Do nothing. The view is already loaded.
} else {
var frame = scrollView.bounds
frame.origin.x = frame.size.width * CGFloat(page)
frame.origin.y = 0.0
let rowData: NSDictionary = arrGallery[page] as! NSDictionary
let urlString: String = rowData["pic"] as! String
let imgURL = NSURL(string: urlString)
// If this image is already cached, don't re-download
if let img = imageCache[urlString] {
let newPageView = UIImageView(image: img)
newPageView.contentMode = .ScaleAspectFit
newPageView.frame = frame
scrollView.addSubview(newPageView)
pageViews[page] = newPageView
}
else {
// The image isn't cached, download the img data
// We should perform this in a background thread
let request: NSURLRequest = NSURLRequest(URL: imgURL!)
let mainQueue = NSOperationQueue.mainQueue()
NSURLConnection.sendAsynchronousRequest(request, queue: mainQueue, completionHandler: { (response, data, error) -> Void in
if error == nil {
// Convert the downloaded data in to a UIImage object
let image = UIImage(data: data!)
// Store the image in to our cache
dispatch_async(dispatch_get_main_queue(), {
self.imageCache[urlString] = image
// Update the cell
let newPageView = UIImageView(image: image)
newPageView.contentMode = .ScaleAspectFit
newPageView.frame = frame
self.scrollView.addSubview(newPageView)
// 4
self.pageViews[page] = newPageView
})
}
else {
print("Error: \(error!.localizedDescription)")
}
})
}
}
我收到的崩溃是：
2016-05-11 13：28：58.743 The Britannia [19024：7909175]收到记忆 警告。
谢谢！
更新：
我已经使用SDWebImage在图像上实现了延迟加载，你的答案和新代码是：
func loadPage(page: Int) {
if page < 0 || page >= arrGallery.count {
// If it's outside the range of what you have to display, then do nothing
return
}
if let page = pageViews[page] {
// Do nothing. The view is already loaded.
} else {
var frame = scrollView.bounds
frame.origin.x = frame.size.width * CGFloat(page)
frame.origin.y = 0.0
let rowData: NSDictionary = arrGallery[page] as! NSDictionary
let urlString: String = rowData["pic"] as! String
let imgURL = NSURL(string: urlString)
// If this image is already cached, don't re-download
if let img = imageCache[urlString] {
let newPageView = UIImageView(image: img)
newPageView.contentMode = .ScaleAspectFit
newPageView.frame = frame
scrollView.addSubview(newPageView)
pageViews[page] = newPageView
}
else {
SDWebImageManager.sharedManager().downloadImageWithURL(imgURL, options: [],progress: nil, completed: {[weak self] (image, error, cached, finished, url) in
if error == nil {
// let image = UIImage(data: data!)
//On Main Thread
dispatch_async(dispatch_get_main_queue()){
self!.imageCache[urlString] = image
// Update the cell
let newPageView = UIImageView(image: image)
newPageView.contentMode = .ScaleAspectFit
newPageView.frame = frame
self!.scrollView.addSubview(newPageView)
// 4
self!.pageViews[page] = newPageView
}
}
else {
print("Error: \(error!.localizedDescription)")
}
})
}
return
}
}
谢谢！