使用 API 中的数据填充 UITableView

Question

我正在尝试使用

UITableView

设置一个提要页面，从 Node.js API 检索所有 JSON 数据。

看起来它正在工作，但它非常慢，有时无法检索所有图像。有没有办法让它完全工作，并优化代码？

import UIKit

class homeViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {

@IBOutlet weak var tableView: UITableView!


var jsonData : [NSDictionary] = [NSDictionary]()
var imageUrls: NSDictionary = NSDictionary()
var urlsArray: [NSURL]! = [NSURL]()


override func viewDidLoad() {
    super.viewDidLoad()

    self.tableView.reloadData()
    
    let qualityOfServiceClass = QOS_CLASS_BACKGROUND
    let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
    dispatch_async(backgroundQueue, {
        println("This is run on the background queue")
        self.refreshData()
        self.getImage()
        
        dispatch_async(dispatch_get_main_queue(), { () -> Void in
            println("This is run on the main queue, after the previous code in outer block")
            self.tableView.reloadData()
        })
    })
                     
}

override func viewWillAppear(animated: Bool) {
                 
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}
        

func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {

    
   return jsonData.count
          

}


func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {

    
    var type = jsonData[indexPath.row]["type"] as! Int
    
    if type == 1 {
   
        
        println("Type= \(type)")
        
        let cell1 : cellTableViewCell = self.tableView.dequeueReusableCellWithIdentifier("cell") as! cellTableViewCell
        
        
        //If images url are retrieved, load them. Otherwise, load the placeholders
        if self.urlsArray.isEmpty == false {
        
            println("Tiè: \(self.urlsArray[indexPath.row])")
            
            
            if let data = NSData(contentsOfURL: self.urlsArray[indexPath.row]) {
        
                    cell1.profileImg?.image = UIImage(data: data)
        
                }
        
        } else {
        
            cell1.profileImg?.image = UIImage(named: "placeholder.png")
        
        }
        
        
        cell1.testLbl.text = (self.jsonData[indexPath.row]["author"] as? String)!
    
        return cell1
        
    } else {
    
    
        let cell2 : cell2TableViewCell = self.tableView.dequeueReusableCellWithIdentifier("cell2") as! cell2TableViewCell
        
       
        return cell2
    }
}


func refreshData()   {


    let requestURL = NSURL(string:"http://adall.ga/api/feeds/author/mat/0")!
    
    
    var request = NSMutableURLRequest(URL: requestURL)
    request.HTTPMethod = "GET"
    
    
    
    request.addValue(userToken, forHTTPHeaderField: "tb-token")
    
    let session = NSURLSession.sharedSession()
    
    let task = session.dataTaskWithRequest(request) {
        data, response, error in
        
        
        println(response)
        
        var dataString = NSString(data: data, encoding: NSUTF8StringEncoding)
        
        println(dataString)
        
        //let jsonResult : NSDictionary = (NSJSONSerialization.JSONObjectWithData(data!, options: NSJSONReadingOptions.MutableContainers, error: nil) as? NSDictionary)!
        //jsonData = (NSJSONSerialization.JSONObjectWithData(data!, options:NSJSONReadingOptions.MutableContainers , error: nil) as? NSArray)!
        
        
        self.jsonData = NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.AllowFragments, error: nil) as! [NSDictionary]
        
        
        
    }
    
    task.resume()
    
    var index: Int
    for index = 0; index < 10000; ++index {
        print("Index: \(index), Task state: \(task.state)")
    }
}

    
func getImage() {
    
    var i = 0
    
    for jsonSingleData in jsonData {
    
        let author = jsonSingleData["author"] as! String
        
                    
        let requestURL2 = NSURL(string: "http://adall.ga/api/users/" + author + "/image")!
        
        println("request: \(requestURL2)")
        
        
        var request2 = NSMutableURLRequest(URL: requestURL2)
        request2.HTTPMethod = "GET"
        
        
        request2.addValue(userToken!, forHTTPHeaderField: "tb-token")
       
        
        let session2 = NSURLSession.sharedSession()
        
        let task2 = session2.dataTaskWithRequest(request2) {
            data, response, error in
            
            
            println("response= \(response)")
           
            
            var dataString = NSString(data: data, encoding: NSUTF8StringEncoding)
            println(dataString)
            
           
            
            self.imageUrls = (NSJSONSerialization.JSONObjectWithData(data, options: NSJSONReadingOptions.MutableContainers, error: nil) as! NSDictionary)
            
            
            //check if exists
            let imageUrl = self.imageUrls["url"] as! String
            
            let url = NSURL(string: "http://" +  imageUrl)
            
            self.urlsArray.append(url!)
            
            println(self.urlsArray)
            
            
            }
        
        task2.resume()
        
        
    }
}

Answer 1

嗨，您可以使用SDWebImage加载图像，它将为您处理所有繁重的工作和缓存。方法如下：

// Here we use the new provided sd_setImageWithURL: method to load the web image
[cell.imageView sd_setImageWithURL:[NSURL URLWithString:@"http://www.domain.com/path/to/image.jpg"]
                      placeholderImage:[UIImage imageNamed:@"placeholder.png"]
                             completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {... completion code here ...}];

这是一个 Swift 示例