![](/img/trans.png)
[英]Redifine a parent properties as controller into a child properties in swift
[英]Swift, Access parent properties in child class
我的問題是我不知道如何訪問子類中的父級屬性
class imageOverlayRenderer: MKOverlayRenderer {
var bar = self.overlay
}
MKOverlayRenderer應該具有屬性覆蓋
我真正想要的是編寫一個MKOverlayRender的自定義子類來渲染圖像,Objective C中的代碼是:
#import <MapKit/MapKit.h>
@interface PVParkMapOverlayView : MKOverlayRenderer
- (instancetype)initWithOverlay:(id<MKOverlay>)overlay overlayImage:(UIImage *)overlayImage;
@end
和
#import "PVParkMapOverlayView.h"
@interface PVParkMapOverlayView ()
@property (nonatomic, strong) UIImage *overlayImage;
@end
@implementation PVParkMapOverlayView
- (instancetype)initWithOverlay:(id<MKOverlay>)overlay overlayImage:(UIImage *)overlayImage {
self = [super initWithOverlay:overlay];
if (self) {
_overlayImage = overlayImage;
}
return self;
}
- (void)drawMapRect:(MKMapRect)mapRect zoomScale:(MKZoomScale)zoomScale inContext:(CGContextRef)context {
CGImageRef imageReference = self.overlayImage.CGImage;
MKMapRect theMapRect = self.overlay.boundingMapRect;
CGRect theRect = [self rectForMapRect:theMapRect];
CGContextScaleCTM(context, 1.0, -1.0);
CGContextTranslateCTM(context, 0.0, -theRect.size.height);
CGContextDrawImage(context, theRect, imageReference);
}
@end
您不能在常規屬性聲明中引用self
您必須聲明屬性lazy
:
class imageOverlayRenderer: MKOverlayRenderer {
lazy var bar: MKOverlay! = self.overlay
}
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.