iphone - 在 UIView 中存储额外的关联信息

Question

我已经阅读了很多有关 SO 上的手势识别器的文章 - 并设法编写了一个工作代码，当在 UIImage 上识别出长按时，会出现一个操作表:

{ ...
 UILongPressGestureRecognizer *longPressWall = [[[UILongPressGestureRecognizer alloc]
                                                               initWithTarget:self     action:@selector(deleteImage:)] autorelease];
                     longPressWall.minimumPressDuration = 0.4;
                     l.userInteractionEnabled=YES;
                     [l addGestureRecognizer:longPressWall];
... }


-(void)deleteImage:(UILongPressGestureRecognizer*)sender { 
    if(UIGestureRecognizerStateBegan == sender.state) {
        UIActionSheet *as = [[UIActionSheet alloc] initWithTitle:@"" delegate:self cancelButtonTitle:@"Close" destructiveButtonTitle:@"Delete Screenshot" otherButtonTitles: nil];
        [as showInView:masterView];
        [as release];
    }
}

因此，在这种情况下，向选择器 deleteImage: 发送信息有点棘手。 我想在调用 deleteImage 时向服务器发送 HTTP 请求，因此我需要来自 View 的一些信息。

有没有办法将信息存储到 UIImageView 中并从 sender.view.myinfo 中检索(例如)？

Answer 1

通过扩展，您可以将属性添加到 UIView存储您的关联值，如下所示:

import Foundation
import ObjectiveC

extension UIImageView
{
    struct Static {
        static var key = "key"
    }
    var myInfo:AnyObject? {
        get { 
            return objc_getAssociatedObject( self, &Static.key ) as AnyObject? 
        }
        set { 
            objc_setAssociatedObject( self, &Static.key,  newValue, .OBJC_ASSOCIATION_RETAIN) 
        }
    }
}

现在您可以在代码的任何地方执行此操作

let anImageView = UIView()

// set your new property on any UIView:
anImageView.myInfo = <some object>

// get your proeprty from any UIView
myImage = anImageView.myInfo

---

上一个答案(相同的代码，但在 Objective-C 中) 查看objc_setAssociatedObject()在 <objc/runtime.h>

我会将其实现为一个类别..(ARC 风格)

#import <objc/runtime.h>

@interface UIImageView (MyInfo)
@property ( nonatomic, strong ) id myInfo ;
@end

@implementation UIImageView (MyInfo)

-(void)setMyInfo:(id)info
{
    objc_setAssociatedObject( self, "_myInfo", info, OBJC_ASSOCIATION_RETAIN_NONATOMIC ) ;
}

-(id)myInfo
{
   return objc_getAssociatedObject( self, "_myInfo" ) ;
}

@end

现在你可以这样做了:

UIImage * myImage ;
myImage.myInfo = <some object>