如何实现“swift的didset”在objective-c？ [英] How to implement the "didset of swift" in objective-c?

问题描述

Swift（摘自由 http://www.raywenderlich.com发布的书iOS教程中的动画：第12章） / ）：

  let photoLayer = CALayer（）
 
 @IBInspectable 
 var image：UIImage！ {
 didSet {
 photoLayer.contents = image.CGImage 
} 
} 
  

如何在objective-c中实现上述语法？
我知道只设置photoLayer和图像的属性如下：

  @property（strong，nonatomic）CALayer * photoLayer; 
 @property（strong，nonatomic）IBInspectable UIImage * image;但是我不知道如何实现 didset {...}      / code> parts使用objective-c语法，请帮助！
解决方案
重写setter并自己实现setter。 
   - （void）setImage：（UIImage *）image {
 _image = image; 
 photoLayer.contents = image.CGImage 
} 
  
 
Swift (from the book 《iOS Animations by Tutorials:Chapter 12》 released by http://www.raywenderlich.com/):
let photoLayer = CALayer()

@IBInspectable
  var image: UIImage! {
    didSet {
      photoLayer.contents = image.CGImage
    }
}
How can I implement the above syntax in objective-c?
I know only to set the property of photoLayer and image like below:
@property (strong, nonatomic) CALayer *photoLayer;
@property (strong, nonatomic) IBInspectable UIImage *image;
But i do not know how to implement didset{...} parts using objective-c syntax, please help!
解决方案
override the setter and implement the setter yourself.
- (void)setImage:(UIImage*)image {
    _image = image;
    photoLayer.contents = image.CGImage
}


                        
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