so what I currently wish to accomplish is for an image to be printed on the background of the IOS simulator screen, so inside of my viewDidLoad, I have this
var img = UIImage(named: "paper.jpg")
This can create the image variable, but I haven't found how to display it on the screen yet. It may seem like a trivial problem, but I haven't found any documentation on this online after searching for awhile. Thanks for reading.
Refer to the UIColor documentation.
In Swift, you have to call a convenience initializer. This is because in Swift, all Objective-C class methods which return an instance of their class become convenience initializers.
Here's how it looks in Swift:
self.view.backgroundColor = UIColor(patternImage: UIImage(named: "paper.jpg"))
+ (UIColor *)colorWithPatternImage:(UIImage *)image returns a UIColor instance, so it will become a convenience initializer in Swift. Similarly, UIImage imageNamed: becomes init(patternImage image: UIImage!).
since this is the marked answer, I felt the need to add a bit more code for completion.
as #senior has posted in his answer another way to add an image to your background is by the use of adding a UIImageView as a subview like so:
let img = UIImage(named: "paper.jpg")
let imgView = UIImageView(image: img)
self.view.addSubview(imgView)
You have to add your image to an ImageView and add this to the current view as a subview,
let img = UIImage(named: "paper.jpg")
let imgView = UIImageView(image: img)
self.view.addSubview(imgView)
Related
I have a UIImageView whose user interaction is true and to which I have given a tap gesture recognizer, whose action handler is as follows:
#IBAction func tap(_ sender:UITapGestureRecognizer) {
let iv = sender.view as! UIImageView
let im = iv.image!
let im2 = UIGraphicsImageRenderer(size:im.size).image { _ in
UIColor.red.setFill()
UIBezierPath(rect: CGRect(origin:.zero, size:im.size)).fill()
}
iv.image = im2
}
I expect the image displayed, when I tap the image view, to be replaced by a solid red image. This works fine on my High Sierra machine running Xcode 9.4. But on my Sierra MacBook running Xcode 9.2, nothing visibly happens.
It's weird. By pausing in the debugger, I can see that the new image is being constructed correctly:
The image is being replaced, but the image view isn't being redrawn. Adding calls like setNeedsDisplay does nothing.
Moreover, if I then proceed to replace the image view's image with a different image, I see the red image!
iv.image = im2
delay(0.5) {
iv.image = im // causes im2 to appear!
}
Some sort of behind-the-scenes caching is evidently causing the image view to get behind in its display by one image.
Can anyone shed light on this? It's presumably a bug in iOS itself, and perhaps in 9.2 specifically; how would one work around it? (Obviously one could substitute another image view wholesale, but that wouldn't tell us what's going on with the caching.)
This seems to be a workaround:
iv.image = im2
delay(0.05) {
iv.image = nil
iv.image = im2
}
But what a horror... Omitting any of those assignments, or reducing the delay to zero (e.g. by calling DispatchQueue.main.async instead), causes the workaround to fail.
Encountered this problem in Xcode 13. Set the contentModel to center in the xib file
or
iv.contentMode = .center
Recently I encountered this code:-
self.view.layer.contents = (id)[UIImage imageNamed:#"img_bg.png"].CGImage;
This setup a background for the whole view of a UIViewController.
Usually, I would just set an UIImageView as subview, taking the whole area of the view from the UIViewController
Why would someone use one technique rather than an other ?
I found this one a bit disturbing because the background does not show in the storyboard; where I expect it.
that's a great question. Deeply, you are asking the different between View and Layer, you know we can think view as layer's delegate which can handle user's interaction with app or system. when there is no any interaction but render view, we can just use layer, that will take up less memory compared with the view。
Try this
self.view.backgroundColor = UIColor(patternImage: UIImage(named:"img_bg.png"))
Hope this will help
Cheers
You can try this:-
UIGraphicsBeginImageContext(self.view.frame.size)
UIImage(named: "img_bg.png")?.drawInRect(self.view.bounds)
let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
self.view.backgroundColor = UIColor(patternImage: image)
Hope this helps,
Thanks
For some reason I am unable to add a UIImageView to my app. This is the code I am using and I have searched for quite a while to figure this out but haven't had any luck.
super.viewDidLoad()
let cloudimage = UIImage(named: "cloud")
let cloudView = UIImageView(image: cloudimage)
self.view.addSubview(cloudView)
cloudView.frame = CGRectMake(0,0,100,200)
The image is a .png in my assets folder so I don't think it's that. I do have auto layout settings enabled if that is an issue? I know it can be an issue with moving a UIImageView around by using its frame, but I think I should still be able to place the image in the View no problem with this code.
I am not quite sure what to do any suggestions would be great, this is extremely frustrating.
If your image is nil, your UIImageView will not render anything. Try debug your view hierarchy.
https://developer.apple.com/library/tvos/documentation/DeveloperTools/Conceptual/debugging_with_xcode/chapters/special_debugging_workflows.html
http://www.raywenderlich.com/98356/view-debugging-in-xcode-6
you need to add UIimageview to main view.
self.view.addSubview(cloudView)
Try by giving the image extension also while setting to UIImage
let cloudimage = UIImage(named: "cloud.png")
let cloudView = UIImageView(image: cloudimage)
cloudView.frame = CGRectMake(0,0,100,200)
self.view.addSubview(cloudView)
Checked and its working.
I am creating an app in which i draw something over imageview using a sublayer function, now i want to create a copy of that image view (over which there is everything like sublayers and image) so that my original imageview don't get effected while accessing imageview for some other purposes. Is it possible to create a copy of image view containing all the contents and use that imageview again and again for different purposes.
Thanks
I'm not sure if you're trying to copy only the contained UIImage, or an image of all the layers. Examples for both:
import UIKit
// Original UIImageView
var imageView = UIImageView()
// Copying image into new UIImageView
var _imageView = UIImageView(image: imageView.image)
// Rendering everything inside the UIImageView into a new UIImageView
UIGraphicsBeginImageContextWithOptions(_imageView.bounds.size, _imageView.opaque, 0.0);
_imageView.layer.renderInContext(UIGraphicsGetCurrentContext())
let allLayersImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
var __imageView = UIImageView(image: allLayersImage)
iOS automatically flips the entire ViewController when using a RTL language like Arabic and does a great job with most of the layout, especially text. The default behavior is to flip the layout but leave UIImageViews the same orientation (since you generally don't want to reverse images).
Is there a way to specify that some images should be flipped (such as arrows) when the phone is set to a RTL language?
iOS 9 includes the imageFlippedForRightToLeftLayoutDirection method that you can use, that automatically flips the image in a UIImageView when in an RTL localization.
The best solution I found to date is marking the image in the assets file as mirror.
We can use imageFlippedForRightToLeftLayoutDirection which returns flipped image if current language is RTL(right to left). i.e
Objective-c
UIImage * flippedImage = [[UIImage imageNamed:#"imageName"] imageFlippedForRightToLeftLayoutDirection];
Swift 3
let flippedImage = UIImage(named: "imageName")?.imageFlippedForRightToLeftLayoutDirection()
Source: Apple Docs
You have to manually flip the UIImages in the UIImageViews you want when the phone is set to a RTL language. This can be easily achieved with this code:
UIImage* defaultImage = [UIImage imageNamed:#"default.png"];
UIImage* flipImage = [UIImage imageWithCGImage:sourceImage.CGImage scale:1.0 orientation: UIImageOrientationUpMirrored];
myImageview.image = flipImage;
I ended up using localized images for the forward and back arrows. This had the advantage of not having to add code each place the image was used and gives the opportunity to clean up the arrows if there are gradients that don't work well flipped.
While we wait for iOS 9 improved right to left support you could create a UIImageView subclass and override setImage to mirror inside the images as #nikos-m suggests and calling super.image = flipImage.
That way you can easily set all the images views you want to flip using custom classes in Interface Builder instead of having to add IBOutlets.
Swift 5
If you want to individualize the image flip, you can register each image with the direction you want since the layout direction is a trait:
let leftToRight = UITraitCollection(layoutDirection: .leftToRight)
let rightToLeft = UITraitCollection(layoutDirection: .rightToLeft)
let imageAsset = UIImageAsset()
let leftToRightImage = UIImage(named: "leftToRightImage")!
let rightToLeftImage = UIImage(named: "rightToLeftImage")!
imageAsset.register(leftToRightImage, with: leftToRight)
imageAsset.register(rightToLeftImage, with: rightToLeft)
This is the same as configuring it in the asset catalogue as #SergioM answered.