在我的视图控制器中我有：
@IBOutlet var worldmapview: Worldmapview!
var eventLayer:CALayer=CALayer();
和一些功能：
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;
}
}
In my viewDidAppear(animated: Bool) method我尝试在世界地图视图中显示图像
以下代码无需任何后台任务即可正常工作。图像立即显示。
// works
let thepicturelayer=create_picture_layer("mypicpath")
eventLayer.addSublayer(thepicturelayer);
worldmapview.layer.addSublayer(eventLayer);
eventLayer.setNeedsDisplay();
在后台任务中并在主要任务中刷新它对我不起作用。图片未显示。一段时间后它就会出现，但并非总是如此。
// 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();
})
})
Update
我用同样的方式添加了一个新的 CAShapelayer 来更新代码，它会立即显示。我不明白其中的区别。在后台任务中创建时，不会显示图片。
UPDATE2
我还意识到一些令我困惑的事情：
以下没有后台任务的代码的工作方式如上所述：
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，图片不会出现。大概是有什么关系吧？好像Calayer的内容没有了？
