我想从我的应用程序中的URL加载一个图像，所以我首先尝试使用Objective-C然后使用Swift，我有一个编译错误：
'imageWithData'不可用：使用对象构造'UIImage（data :)'
我的功能：
@IBOutlet var imageView : UIImageView
override func viewDidLoad() {
super.viewDidLoad()
var url:NSURL = NSURL.URLWithString("http://myURL/ios8.png")
var data:NSData = NSData.dataWithContentsOfURL(url, options: nil, error: nil)
imageView.image = UIImage.imageWithData(data)// Error here
}
在Objective-C中：
- (void)viewDidLoad {
[super viewDidLoad];
NSURL *url = [NSURL URLWithString:(@"http://myURL/ios8.png")];
NSData *data = [NSData dataWithContentsOfURL:url];
_imageView.image = [UIImage imageWithData: data];
_labelURL.text = @"http://www.quentinroussat.fr/assets/img/iOS%20icon's%20Style/ios8.png";
}
有人可以解释一下为什么imageWithData:不适用于Swift，我该如何解决这个问题。
Xcode 8或更高版本•Swift 3或更高版本
同步：
if let filePath = Bundle.main.path(forResource: "imageName", ofType: "jpg"), let image = UIImage(contentsOfFile: filePath) {
imageView.contentMode = .scaleAspectFit
imageView.image = image
}
异步：
使用完成处理程序创建一个方法，以从您的网址获取图像数据
func getData(from url: URL, completion: @escaping (Data?, URLResponse?, Error?) -> ()) {
URLSession.shared.dataTask(with: url, completionHandler: completion).resume()
}
创建下载图像的方法（启动任务）
func downloadImage(from url: URL) {
print("Download Started")
getData(from: url) { data, response, error in
guard let data = data, error == nil else { return }
print(response?.suggestedFilename ?? url.lastPathComponent)
print("Download Finished")
DispatchQueue.main.async() {
self.imageView.image = UIImage(data: data)
}
}
}
用法：
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
print("Begin of code")
let url = URL(string: "https://cdn.arstechnica.net/wp-content/uploads/2018/06/macOS-Mojave-Dynamic-Wallpaper-transition.jpg")!
downloadImage(from: url)
print("End of code. The image will continue downloading in the background and it will be loaded when it ends.")
}
延期：
extension UIImageView {
func downloaded(from url: URL, contentMode mode: UIViewContentMode = .scaleAspectFit) { // for swift 4.2 syntax just use ===> mode: UIView.ContentMode
contentMode = mode
URLSession.shared.dataTask(with: url) { data, response, error in
guard
let httpURLResponse = response as? HTTPURLResponse, httpURLResponse.statusCode == 200,
let mimeType = response?.mimeType, mimeType.hasPrefix("image"),
let data = data, error == nil,
let image = UIImage(data: data)
else { return }
DispatchQueue.main.async() {
self.image = image
}
}.resume()
}
func downloaded(from link: String, contentMode mode: UIViewContentMode = .scaleAspectFit) { // for swift 4.2 syntax just use ===> mode: UIView.ContentMode
guard let url = URL(string: link) else { return }
downloaded(from: url, contentMode: mode)
}
}
用法：
imageView.downloaded(from: "https://cdn.arstechnica.net/wp-content/uploads/2018/06/macOS-Mojave-Dynamic-Wallpaper-transition.jpg")
Swift 4：一个用于小图像的简单加载器（例如：缩略图），它使用NSCache并始终在主线程上运行：
class ImageLoader {
private static let cache = NSCache<NSString, NSData>()
class func image(for url: URL, completionHandler: @escaping(_ image: UIImage?) -> ()) {
DispatchQueue.global(qos: DispatchQoS.QoSClass.background).async {
if let data = self.cache.object(forKey: url.absoluteString as NSString) {
DispatchQueue.main.async { completionHandler(UIImage(data: data as Data)) }
return
}
guard let data = NSData(contentsOf: url) else {
DispatchQueue.main.async { completionHandler(nil) }
return
}
self.cache.setObject(data, forKey: url.absoluteString as NSString)
DispatchQueue.main.async { completionHandler(UIImage(data: data as Data)) }
}
}
}
用法：
ImageLoader.image(for: imageURL) { image in
self.imageView.image = image
}
Swift 4 ::
这将在加载图像时显示加载程序。您可以使用临时存储图像的NSCache
let imageCache = NSCache<NSString, UIImage>()
extension UIImageView {
func loadImageUsingCache(withUrl urlString : String) {
let url = URL(string: urlString)
if url == nil {return}
self.image = nil
// check cached image
if let cachedImage = imageCache.object(forKey: urlString as NSString) {
self.image = cachedImage
return
}
let activityIndicator: UIActivityIndicatorView = UIActivityIndicatorView.init(activityIndicatorStyle: .gray)
addSubview(activityIndicator)
activityIndicator.startAnimating()
activityIndicator.center = self.center
// if not, download image from url
URLSession.shared.dataTask(with: url!, completionHandler: { (data, response, error) in
if error != nil {
print(error!)
return
}
DispatchQueue.main.async {
if let image = UIImage(data: data!) {
imageCache.setObject(image, forKey: urlString as NSString)
self.image = image
activityIndicator.removeFromSuperview()
}
}
}).resume()
}
}
用法：-
truckImageView.loadImageUsingCache(withUrl: currentTruck.logoString)
你想要做的：
UIImage(data: data)
在Swift中，他们用常规构造函数替换了大多数Objective C工厂方法。
看到：
Swift 2有错误句柄和自定义请求标头
只需添加扩展到UIImageView：
extension UIImageView {
public func imageFromUrl(urlString: String) {
if let url = NSURL(string: urlString) {
let request = NSMutableURLRequest(URL: url)
request.setValue("<YOUR_HEADER_VALUE>", forHTTPHeaderField: "<YOUR_HEADER_KEY>")
NSURLSession.sharedSession().dataTaskWithRequest(request) {
(data, response, error) in
guard let data = data where error == nil else{
NSLog("Image download error: \(error)")
return
}
if let httpResponse = response as? NSHTTPURLResponse{
if httpResponse.statusCode > 400 {
let errorMsg = NSString(data: data, encoding: NSUTF8StringEncoding)
NSLog("Image download error, statusCode: \(httpResponse.statusCode), error: \(errorMsg!)")
return
}
}
dispatch_async(dispatch_get_main_queue(), {
NSLog("Image download success")
self.image = UIImage(data: data)
})
}.resume()
}
}
}
然后，使用新的imageFromUrl(urlString: String)下载图像
用法：
imageView.imageFromUrl("https://i.imgur.com/ONaprQV.png")
斯威夫特4
此方法将异步下载网站中的图像并将其缓存：
func getImageFromWeb(_ urlString: String, closure: @escaping (UIImage?) -> ()) {
guard let url = URL(string: urlString) else {
return closure(nil)
}
let task = URLSession(configuration: .default).dataTask(with: url) { (data, response, error) in
guard error == nil else {
print("error: \(String(describing: error))")
return closure(nil)
}
guard response != nil else {
print("no response")
return closure(nil)
}
guard data != nil else {
print("no data")
return closure(nil)
}
DispatchQueue.main.async {
closure(UIImage(data: data!))
}
}; task.resume()
}
正在使用：
getImageFromWeb("http://www.apple.com/euro/ios/ios8/a/generic/images/og.png") { (image) in
if let image = image {
let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
imageView.image = image
self.view.addSubview(imageView)
} // if you use an Else statement, it will be in background
}
Swift 2.0：
1)
if let url = NSURL(string: "http://etc...") {
if let data = NSData(contentsOfURL: url) {
imageURL.image = UIImage(data: data)
}
}
要么
imageURL.image =
NSURL(string: "http:// image name...")
.flatMap { NSData(contentsOfURL: $0) }
.flatMap { UIImage(data: $0) }
2）将此方法添加到VC或Extension。
func load_image(urlString:String)
{ let imgURL: NSURL = NSURL(string: urlString)!
let request: NSURLRequest = NSURLRequest(URL: imgURL)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) { (response: NSURLResponse?, data: NSData?, error: NSError?) in
if error == nil {
self.image_element.image = UIImage(data: data)
}
}
}
用法：
self.load_image(" url strig here")
如果您正在寻找一个非常简单的实现。 （这在Swift 2中对我有用）
let imageURL = NSURL(string: "https://farm2.staticflickr.com/1591/26078338233_d1466b7da2_m.jpg")
let imagedData = NSData(contentsOfURL: imageURL!)!
imageView?.image = UIImage(data: imagedData)
我在tableview中实现了一个只有图像的自定义单元格
func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell{
let cell = tableView.dequeueReusableCellWithIdentifier("theCell", forIndexPath: indexPath) as! customTableViewCell
let imageURL = NSURL(string: "https://farm2.staticflickr.com/1591/26078338233_d1466b7da2_m.jpg")
let imagedData = NSData(contentsOfURL: imageURL!)!
cell.imageView?.image = UIImage(data: imagedData)
return cell
}
Kingfisher是将图像加载到URL的最佳库之一。
Github网址 - https://github.com/onevcat/Kingfisher
// If you want to use Activity Indicator.
imageview_pic.kf.indicatorType = .activity
imageview_pic.kf.setImage(with: URL(string: "Give your url string"))
// If you want to use custom placeholder image.
imageview_pic.kf.setImage(with: URL(string: "Give your url string"), placeholder: UIImage(named: "placeholder image name"), options: nil, progressBlock: nil, completionHandler: nil)
获取安全的图像并使用Swift 2.0和X-Code 7.1的方法：
static func imageForImageURLString(imageURLString: String, completion: (image: UIImage?, success: Bool) -> Void) {
guard let url = NSURL(string: imageURLString),
let data = NSData(contentsOfURL: url),
let image = UIImage(data: data)
else {
completion(image: nil, success: false);
return
}
completion(image: image, success: true)
}
然后你会这样调用这个方法：
imageForImageURLString(imageString) { (image, success) -> Void in
if success {
guard let image = image
else { return } // Error handling here
// You now have the image.
} else {
// Error handling here.
}
}
如果要使用图像更新视图，则必须在“if success {”之后使用此视图：
dispatch_async(dispatch_get_main_queue()) { () -> Void in
guard let image = image
else { return } // Error handling here
// You now have the image. Use the image to update the view or anything UI related here
// Reload the view, so the image appears
}
如果在UI中使用图像，则需要最后一部分的原因是因为网络调用需要时间。如果您尝试使用图像更新UI而不调用上面的dispatch_async，计算机将在图像仍然被提取时查找图像，发现没有图像（尚未），并继续前进，就好像没有图像一样找到。将代码放入dispatch_async完成闭包中对计算机说：“转到，获取此图像，完成后再完成此代码。”这样，您将在调用代码时获得图像，并且事情会很好。
我建议使用Kingfisher库异步下载图像。关于使用Kingfisher的最好的部分是，它默认缓存所有下载的图像，图像url作为id。下次当您请求使用该特定URl下载图像时，它将从缓存加载它。
用法：
newsImage.kf.setImage(with: imageUrl!, placeholder: nil, options: nil, progressBlock: nil, completionHandler: { (image, error, cacheType, imageUrl) in
if error == nil{
self.activityIndicator.stopAnimating()
}else if error != nil{
self.activityIndicator.stopAnimating()
}
})
（Swift 4更新）要直接回答原始问题，这里是发布的Objective-C片段的快速等价物。
let url = URL(string: image.url)
let data = try? Data(contentsOf: url!) //make sure your image in this url does exist, otherwise unwrap in a if let check / try-catch
imageView.image = UIImage(data: data!)
免责声明：
重要的是要注意Data(contentsOf:)方法将在执行代码的同一线程中同步下载url的内容，因此不要在应用程序的主线程中调用它。
一种简单的方法是使相同的代码异步运行，而不是阻止UI，这是使用GCD：
let url = URL(string: image.url)
DispatchQueue.global().async {
let data = try? Data(contentsOf: url!) //make sure your image in this url does exist, otherwise unwrap in a if let check / try-catch
DispatchQueue.main.async {
imageView.image = UIImage(data: data!)
}
}
也就是说，在现实生活中的应用程序中，如果您希望获得最佳用户体验并避免多次下载同一图像，您可能还希望它们不仅可以下载，还可以缓存。已经有相当多的库可以非常无缝地完成，它们都非常易于使用。我个人推荐Kingfisher：
import Kingfisher
let url = URL(string: "url_of_your_image")
// this downloads the image asynchronously if it's not cached yet
imageView.kf.setImage(with: url)
就是这样
self.yourImage.sd_setImage(with: NSURL(string: StrUrl as String ) as URL!, placeholderImage: placeholderImage, options: SDWebImageOptions(rawValue: 0), completed: { (image, error, cacheType, imageURL) in
if( error != nil)
{
print("Error while displaying image" , (error?.localizedDescription)! as String)
}
})
使用像这样：
func NKPlaceholderImage(image:UIImage?, imageView:UIImageView?,imgUrl:String,compate:@escaping (UIImage?) -> Void){
if image != nil && imageView != nil {
imageView!.image = image!
}
var urlcatch = imgUrl.replacingOccurrences(of: "/", with: "#")
let documentpath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0]
urlcatch = documentpath + "/" + "\(urlcatch)"
let image = UIImage(contentsOfFile:urlcatch)
if image != nil && imageView != nil
{
imageView!.image = image!
compate(image)
}else{
if let url = URL(string: imgUrl){
DispatchQueue.global(qos: .background).async {
() -> Void in
let imgdata = NSData(contentsOf: url)
DispatchQueue.main.async {
() -> Void in
imgdata?.write(toFile: urlcatch, atomically: true)
let image = UIImage(contentsOfFile:urlcatch)
compate(image)
if image != nil {
if imageView != nil {
imageView!.image = image!
}
}
}
}
}
}
}
唯一缺少的是一个！
// Here imgPicture = your imageView
// UIImage(named: "placeholder") is Display image brfore download and load actual image.
NKPlaceholderImage(image: UIImage(named: "placeholder"), imageView: imgPicture, imgUrl: "Put Here your server image Url Sting") { (image) in }
将图像下载到文件的Swift 2.x答案（与Leo Dabus的答案相反，后者将图像存储在内存中）。根据Leo Dabus的回答和Rob在let url = NSURL.URLWithString("http://live-wallpaper.net/iphone/img/app/i/p/iphone-4s-wallpapers-mobile-backgrounds-dark_2466f886de3472ef1fa968033f1da3e1_raw_1087fae1932cec8837695934b7eb1250_raw.jpg");
var err: NSError?
var imageData :NSData = NSData.dataWithContentsOfURL(url!,options: NSDataReadingOptions.DataReadingMappedIfSafe, error: &err)
var bgImage = UIImage(data:imageData!)
的回答：
Get the data from NSURLSession DownloadTaskWithRequest from completion handler
Swift 4.1我创建了一个函数只是传递图像url，生成图像后的缓存键设置为完成块。
// Set download vars
let downloadURL = NSURL() // URL to download from
let localFilename = "foobar.png" // Filename for storing locally
// Create download request
let task = NSURLSession.sharedSession().downloadTaskWithURL(downloadURL) { location, response, error in
guard location != nil && error == nil else {
print("Error downloading message: \(error)")
return
}
// If here, no errors so save message to permanent location
let fileManager = NSFileManager.defaultManager()
do {
let documents = try fileManager.URLForDirectory(.DocumentDirectory, inDomain: .UserDomainMask, appropriateForURL: nil, create: false)
let fileURL = documents.URLByAppendingPathComponent(localFilename)
try fileManager.moveItemAtURL(location!, toURL: fileURL)
self.doFileDownloaded(fileURL, localFilename: localFilename)
print("Downloaded message @ \(localFilename)")
} catch {
print("Error downloading message: \(error)")
}
}
// Start download
print("Starting download @ \(downloadURL)")
task.resume()
// Helper function called after file successfully downloaded
private func doFileDownloaded(fileURL: NSURL, localFilename: String) {
// Do stuff with downloaded image
}
class NetworkManager: NSObject {
private var imageQueue = OperationQueue()
private var imageCache = NSCache<AnyObject, AnyObject>()
func downloadImageWithUrl(imageUrl: String, cacheKey: String, completionBlock: @escaping (_ image: UIImage?)-> Void) {
let downloadedImage = imageCache.object(forKey: cacheKey as AnyObject)
if let _ = downloadedImage as? UIImage {
completionBlock(downloadedImage as? UIImage)
} else {
let blockOperation = BlockOperation()
blockOperation.addExecutionBlock({
let url = URL(string: imageUrl)
do {
let data = try Data(contentsOf: url!)
let newImage = UIImage(data: data)
if newImage != nil {
self.imageCache.setObject(newImage!, forKey: cacheKey as AnyObject)
self.runOnMainThread {
completionBlock(newImage)
}
} else {
completionBlock(nil)
}
} catch {
completionBlock(nil)
}
})
self.imageQueue.addOperation(blockOperation)
blockOperation.completionBlock = {
print("Image downloaded \(cacheKey)")
}
}
}
}
extension NetworkManager {
fileprivate func runOnMainThread(block:@escaping ()->Void) {
if Thread.isMainThread {
block()
} else {
let mainQueue = OperationQueue.main
mainQueue.addOperation({
block()
})
}
}
}
我在class func downloadImageFromUrl(with urlStr: String, andCompletionHandler:@escaping (_ result:Bool) -> Void) {
guard let url = URL(string: urlStr) else {
andCompletionHandler(false)
return
}
DispatchQueue.global(qos: .background).async {
URLSession.shared.dataTask(with: url, completionHandler: { (data, response, error) -> Void in
if error == nil {
let httpURLResponse = response as? HTTPURLResponse
Utils.print( "status code ID : \(String(describing: httpURLResponse?.statusCode))")
if httpURLResponse?.statusCode == 200 {
if let data = data {
if let image = UIImage(data: data) {
ImageCaching.sharedInterface().setImage(image, withID: url.absoluteString as NSString)
DispatchQueue.main.async {
andCompletionHandler(true)
}
}else {
andCompletionHandler(false)
}
}else {
andCompletionHandler(false)
}
}else {
andCompletionHandler(false)
}
}else {
andCompletionHandler(false)
}
}).resume()
}
}
类中创建了一个简单的类函数，用于调用Utils.swift可以访问的方法，并使用classname.methodname类将图像保存在NSCache中
ImageCaching.swift快乐的鳕鱼。干杯：）
如果使用库不是问题，可以在Utils.downloadImageFromUrl(with: URL, andCompletionHandler: { (isDownloaded) in
if isDownloaded {
if let image = ImageCaching.sharedInterface().getImage(URL as NSString) {
self.btnTeam.setBackgroundImage(image, for: .normal)
}
}else {
DispatchQueue.main.async {
self.btnTeam.setBackgroundImage(#imageLiteral(resourceName: "com"), for: .normal)
}
}
})
的帮助下完成。我的样品来自它的AlamofireImage
占位符图像示例：
Github
它有许多方便的功能和扩展来处理图像。从缓存到缩放和调整大小，甚至在图像上应用滤镜。如果图片在您的应用中很重要，我建议您使用此框架并节省您的时间。
使用As Imageview，您可以轻松地在imageview中加载图像网址。
让image1Url：URL = URL（string：“（imageurl）”为String）！ imageview.imageURL = image1Url
从服务器加载图像： -
let imageView = UIImageView(frame: frame)
let url = URL(string: "https://httpbin.org/image/png")!
let placeholderImage = UIImage(named: "placeholder")!
imageView.af_setImage(withURL: url, placeholderImage: placeholderImage)
用法： -
func downloadImage(from url: URL , success:@escaping((_ image:UIImage)->()),failure:@escaping ((_ msg:String)->())){
print("Download Started")
getData(from: url) { data, response, error in
guard let data = data, error == nil else {
failure("Image cant download from G+ or fb server")
return
}
print(response?.suggestedFilename ?? url.lastPathComponent)
print("Download Finished")
DispatchQueue.main.async() {
if let _img = UIImage(data: data){
success(_img)
}
}
}
}
func getData(from url: URL, completion: @escaping (Data?, URLResponse?, Error?) -> ()) {
URLSession.shared.dataTask(with: url, completionHandler: completion).resume()
}
在Swift中使用此代码
if let url = URL(string: "http://www.apple.com/euro/ios/ios8/a/generic/images/og.png") {
self.downloadImage(from:url , success: { (image) in
print(image)
}, failure: { (failureReason) in
print(failureReason)
})
}
如果你只是想加载图像（异步！） - 只需将这个小扩展添加到你的swift代码中：
extension UIImageView {
public func imageFromUrl(urlString: String) {
if let url = NSURL(string: urlString) {
let request = NSURLRequest(URL: url)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {
(response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
if let imageData = data as NSData? {
self.image = UIImage(data: imageData)
}
}
}
}
}
并以这种方式使用它：
myImageView.imageFromUrl("https://robohash.org/123.png")
对于Swift-3及以上版本：
imageView.image=UIImage(data: NSData(contentsOfURL: NSURL(string: "http://myURL/ios8.png")!)!
Swift 2.2 || Xcode 7.3
我得到了惊人的结果!!与AlamofireImage swift库
它提供了多种功能，例如：
并且非常容易实现您的应用程序
Step.1安装pod
Alamofire 3.3.x
在'Alamofire'下
AlamofireImage 2.4.x
在'AlamofireImage'下
Step.2导入和使用
import Alamofire
import AlamofireImage
let downloadURL = NSURL(string: "http://cdn.sstatic.net/Sites/stackoverflow/company/Img/photos/big/6.jpg?v=f4b7c5fee820")!
imageView.af_setImageWithURL(downloadURL)
而已！！它会照顾一切
非常感谢Alamofire guys，让iDevelopers生活轻松;）
Xcode 8•Swift 3
Leo Dabus的答案太棒了！我只是想提供一体化的功能解决方案：
let url = URL(string:
"http://www.apple.com/euro/ios/ios8/a/generic/images/og.png")
let task = URLSession.shared.dataTask(with: url!) { data, response, error in
guard let data = data, error == nil else { return }
DispatchQueue.main.async() { // execute on main thread
self.imageView.image = UIImage(data: data)
}
}
task.resume()
我将问题的最佳答案的代码包装到扩展UIImageView的单个可重用类中，因此您可以直接在故事板中使用异步加载UIImageViews（或者从代码创建它们）。
这是我的班级：
import Foundation
import UIKit
class UIImageViewAsync :UIImageView
{
override init()
{
super.init(frame: CGRect())
}
override init(frame:CGRect)
{
super.init(frame:frame)
}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
func getDataFromUrl(url:String, completion: ((data: NSData?) -> Void)) {
NSURLSession.sharedSession().dataTaskWithURL(NSURL(string: url)!) { (data, response, error) in
completion(data: NSData(data: data))
}.resume()
}
func downloadImage(url:String){
getDataFromUrl(url) { data in
dispatch_async(dispatch_get_main_queue()) {
self.contentMode = UIViewContentMode.ScaleAspectFill
self.image = UIImage(data: data!)
}
}
}
}
以下是如何使用它：
imageView.downloadImage("http://www.image-server.com/myImage.jpg")
let url = NSURL.URLWithString("http://live-wallpaper.net/iphone/img/app/i/p/iphone-4s-wallpapers-mobile-backgrounds-dark_2466f886de3472ef1fa968033f1da3e1_raw_1087fae1932cec8837695934b7eb1250_raw.jpg");
var err: NSError?
var imageData :NSData = NSData.dataWithContentsOfURL(url,options: NSDataReadingOptions.DataReadingMappedIfSafe, error: &err)
var bgImage = UIImage(data:imageData)
仅供参考：适用于swift-2.0 Xcode7.0 beta2
extension UIImageView {
public func imageFromUrl(urlString: String) {
if let url = NSURL(string: urlString) {
let request = NSURLRequest(URL: url)
NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {
(response: NSURLResponse?, data: NSData?, error: NSError?) -> Void in
self.image = UIImage(data: data!)
}
}
}
}
swift 3，错误处理
let url = URL(string: arr[indexPath.row] as! String)
if url != nil {
DispatchQueue.global().async {
let data = try? Data(contentsOf: url!) //make sure your image in this url does exist, otherwise unwrap in a if let check / try-catch
DispatchQueue.main.async {
if data != nil {
cell.imgView.image = UIImage(data:data!)
}else{
cell.imgView.image = UIImage(named: "default.png")
}
}
}
}
随着扩展
extension UIImageView {
func setCustomImage(_ imgURLString: String?) {
guard let imageURLString = imgURLString else {
self.image = UIImage(named: "default.png")
return
}
DispatchQueue.global().async {
let data = try? Data(contentsOf: URL(string: imageURLString)!)
DispatchQueue.main.async {
self.image = data != nil ? UIImage(data: data!) : UIImage(named: "default.png")
}
}
}
}
扩展使用
myImageView。 setCustomImage（ “URL”）