使用Xcode 6.1 / Swift以编程方式将图像设置为UIImageView

Question

I'm trying to set UIImageView programmatically in Xcode 6.1:

@IBOutlet weak var bgImage: UIImageView!

var image : UIImage = UIImage(named:"afternoon")!
bgImage = UIImageView(image: image)
bgImage.frame = CGRect(x: 0, y: 0, width: 100, height: 200)
view.addSubview(bgImage)

But Xcode is saying "expected declaration" with bgImage = UIImageView(image: image) Image "afternoon" is a PNG, and my understanding is PNG does not need an extension in XCode 6.1.

Also tried just bgImage.image = UIImage(named: "afternoon") , but still get:

UPDATE

OK, I have put the code to update UIImageView into the viewDidLoad function, but UIImageView is still not showing the image (which exists in the base directory as afternoon.png):

@IBOutlet weak var bgImage: UIImageView!
@IBOutlet weak var dateLabel: UILabel!
@IBOutlet weak var timeLabel: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    updateTime()
    var timer = NSTimer()
    let aSelector : Selector = "updateTime"
    timer = NSTimer.scheduledTimerWithTimeInterval(0.01, target: self, selector: aSelector, userInfo: nil, repeats: true)

    var image : UIImage = UIImage(named:"afternoon")!
    bgImage = UIImageView(image: image)
}

Answer 1

Since you have your bgImage assigned and linked as an IBOutlet, there is no need to initialize it as a UIImageView... instead all you need to do is set the image property like bgImage.image = UIImage(named: "afternoon") . After running this code, the image appeared fine since it was already assigned using the outlet.

However, if it wasn't an outlet and you didn't have it already connected to a UIImageView object on a storyboard/xib file, then you could so something like the following...

class ViewController: UIViewController {
    var bgImage: UIImageView?

    override func viewDidLoad() {
        super.viewDidLoad()

        var image: UIImage = UIImage(named: "afternoon")!
        bgImage = UIImageView(image: image)
        bgImage!.frame = CGRectMake(0,0,100,200)
        self.view.addSubview(bgImage!)
    }
}

Answer 2

In xcode 8 you can directly choose image from the selection window (NEW)...

• You just need to type - "image" and you will get a suggestion box then select -"Image Literal" from list (see in attached picture) and

• then tap on the square you will be able to see all images(see in
  second attached picture) which are in your image assets... or select other image from there.

• Now tap on square box - (You will see that square box after selecting above option)

Answer 3

OK, got it working with this (creating the UIImageView programmatically):

var imageViewObject :UIImageView

imageViewObject = UIImageView(frame:CGRectMake(0, 0, 600, 600))

imageViewObject.image = UIImage(named:"afternoon")

self.view.addSubview(imageViewObject)

self.view.sendSubviewToBack(imageViewObject)

Answer 4

How about this;

myImageView.image=UIImage(named: "image_1")

where image_1 is within the assets folder as image_1. png .

This worked for me since i'm using a switch case to display an image slide.

Answer 5

This code is in the wrong place:

var image : UIImage = UIImage(named:"afternoon")!
bgImage = UIImageView(image: image)
bgImage.frame = CGRect(x: 0, y: 0, width: 100, height: 200)
view.addSubview(bgImage)

You must place it inside a function. I recommend moving it inside the viewDidLoad function.

In general, the only code you can add within the class that's not inside of a function are variable declarations like:

@IBOutlet weak var bgImage: UIImageView!

Answer 6

With swift syntax this worked for me :

    let leftImageView = UIImageView()
    leftImageView.image = UIImage(named: "email")

    let leftView = UIView()
    leftView.addSubview(leftImageView)

    leftView.frame = CGRect(x: 0, y: 0, width: 40, height: 40)
    leftImageView.frame = CGRect(x: 10, y: 10, width: 20, height: 20)
    userNameTextField.leftViewMode = .always
    userNameTextField.leftView = leftView

Answer 7

In Swift 4, if the image is returned as nil.

Click on image, on the right hand side (Utilities) -> Check Target Membership

Answer 8

If you want to do it the way you showed in your question, this is a way to do it inline

class YourClass: UIViewController{

  @IBOutlet weak var tableView: UITableView!
  //other IBOutlets

  //THIS is how you declare a UIImageView inline
  let placeholderImage : UIImageView = {
        let placeholderImage = UIImageView(image: UIImage(named: "nophoto"))
        placeholderImage.contentMode = .scaleAspectFill
        return placeholderImage
    }()

   var someVariable: String!
   var someOtherVariable: Int!

   func someMethod(){
      //method code
   }

   //and so on
}

Answer 9

You just need to drag and drop an ImageView , create the outlet action, link it, and provide an image (Xcode is going to look in your assets folder for the name you provided (here: "toronto"))

In yourProject/ViewController.swift

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var imgView: UIImageView!

    override func viewDidLoad() {
        super.viewDidLoad()

        imgView.image = UIImage(named: "toronto")
    }
}