在我的视图控制器中,我有以下代码:
在我的
在后台任务中刷新,在主任务中它对我不起作用。图片没有显示。过了一会儿它会出现,但并不总是这样。
@IBOutlet var worldmapview: Worldmapview!
var eventLayer:CALayer=CALayer();
还有一些函数:
func create_picture_layer(pathtopic:String) -> CALayer {
let bm=getImage(pathtopic,fBitmapsizeSelected: 100)!;
var calayer_for_picture=CALayer();
calayer_for_picture.frame=CGRectMake(100, 100, 100, 100);
calayer_for_picture.contents = bm.CGImage;
return calayer_for_picture;
}
func createCircleShape(x:CGFloat,y:CGFloat, size:CGFloat) -> CAShapeLayer {
var test2:UIBezierPath=UIBezierPath(ovalInRect: CGRectMake(x - size/2, y - size/2, size, size));
var shapelayer:CAShapeLayer=CAShapeLayer();
shapelayer.backgroundColor=UIColor.clearColor().CGColor;
//shapelayer.frame=CGRectMake(0, 0, 300, 300);
shapelayer.fillColor=UIColor.darkGrayColor().CGColor;
shapelayer.path=test2.CGPath;
shapelayer.opaque=true
return shapelayer;
}
func getImage(simagename: String, fBitmapsizeSelected:CGFloat) -> UIImage?{
var sPathToImage:String=AppProperties.sharedInstance.sPicturePath + simagename;
let checkValidation = NSFileManager.defaultManager()
if (!checkValidation.fileExistsAtPath(sPathToImage) || simagename.equals("")){
// Path to unknown image
let sunknownimagename:String = "na/na.jpa";
sPathToImage=AppProperties.sharedInstance.sPicturePath + sunknownimagename;
}
let bm:UIImage=UIImage(contentsOfFile: sPathToImage)!;
var bMapScaled:UIImage;
if(!bm.isEqual(nil)){
let newSize:CGSize=CGSizeMake(fBitmapsizeSelected, fBitmapsizeSelected);
bMapScaled = bm.imageByScalingToSize(newSize,contentMode: UIViewContentMode.ScaleAspectFill)!;
return bMapScaled;
}else{
return nil;
}
}
在我的
viewDidAppear(animated: Bool)方法
中,我试图在worldmapview中展示图片。下面的代码在没有任何后台任务的情况下能够正常工作。这张图片将会立即显示。// works
let thepicturelayer=create_picture_layer("mypicpath")
eventLayer.addSublayer(thepicturelayer);
worldmapview.layer.addSublayer(eventLayer);
eventLayer.setNeedsDisplay();
在后台任务中刷新,在主任务中它对我不起作用。图片没有显示。过了一会儿它会出现,但并不总是这样。
// doesn't work
let qualityOfServiceClass = QOS_CLASS_BACKGROUND
let backgroundQueue = dispatch_get_global_queue(qualityOfServiceClass, 0)
dispatch_async(backgroundQueue, {
// geht auch mit Eventlayer
let thepicturelayer=self.create_picture_layer() // This Shape doesn't appear.
let circleshapelayer=self.createCircleShape(200, y: 200, size: 20) // This shape appears immediatelly.
self.eventLayer.addSublayer(thepicturelayer);
self.eventLayer.addSublayer(circleshapelayer);
dispatch_async(dispatch_get_main_queue(),{
//assert(self.eventLayer.sublayers?.count > 0,"no layers in eventLayer !") // just added
self.worldmapview.layer.addSublayer(self.eventLayer);
//assert(self.worldmapview.layer.sublayers!.count > 0,"no layers in worldmapview!" ) // just added
let sublayers=self.eventLayer.sublayers;
if sublayers != nil {
for l in self.eventLayer.sublayers! {
l.setNeedsDisplay()
}
}
//self.updateWorldMapGUI();
self.worldmapview.layer.addSublayer(self.eventLayer);
//thepicturelayer.setNeedsDisplay();
//circleshapelayer.setNeedsDisplay();
self.eventLayer.setNeedsDisplay();
})
})
更新
我使用了同样的方式添加了一个新的CAShapeLayer,它立即显示出来了。但是我不明白其中的区别。当在后台任务中创建图片时,它不会被显示出来。
更新2
我意识到还有一些令我困惑的事情: 以下代码在没有后台任务的情况下就像之前描述的那样运行:
let thepicturelayer=create_picture_layer()
eventLayer.addSublayer(thepicturelayer);
worldmapview.layer.addSublayer(eventLayer);
eventLayer.setNeedsDisplay();
//thepicturelayer.setNeedsDisplay(); // When adding this, the picture is not shown.
但是,激活最后一行时,图片没有出现。可能与此有关?看起来仿佛calayer的内容消失了?
self.create_picture_layer("mypicpath")
是同步的,不会立即返回吗? - SwiftArchitect