NSOperation userInfo字典

Question

有没有一种方法可以让NSOperation的userInfo NSDictionary

基本上，我想给NSOperation分配一个ID，稍后我想检查一下，这个ID是否已经分配给了NSOperation

- (void)processSmthForID:(NSString *)someID {

    for (NSOperation * operation in self.precessQueue.operations) {

        if ([operation.userInfo[@"id"] isEqualToString:someID]) {
            // already doing this for this ID, no need to create another operation
            return;
        }

    }

    NSOperation * newOperation = ...
    newOperation.userInfo[@"id"] = someID;

    // enqueue and execute

}

Answer 1

NSOperation应该是子类化的。只需设计自己的子类即可。

NSOperation类是一个抽象类，用于封装与单个任务关联的代码和数据。因为它是抽象的，所以不直接使用这个类，而是子类化或使用系统定义的子类(NSInvocationOperation或NSBlockOperation)来执行实际任务。

read here

我同意@Daij-Djan关于添加userInfo属性的观点。

这个属性可以作为NSOperation上的一个扩展来实现(请参考他对实现的回答)。

然而，对于NSOperation的标识符的需要是类的专门化(您可以说新类是IdentifiableOperation)

Answer 2

在NSOperation上定义属性，如下所示：

#import <Foundation/Foundation.h>
#import <objc/runtime.h>

//category
@interface NSOperation (UserInfo)
@property(copy) NSDictionary *userInfo;
@end

static void * const kDDAssociatedStorageUserInfo = (void*)&kDDAssociatedStorageUserInfo;

@implementation NSOperation (UserInfo)

- (void)setUserInfo:(NSDictionary *)userInfo {
    objc_setAssociatedObject(self, kDDAssociatedStorageUserInfo, [userInfo copy], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (NSDictionary *)userInfo {
    return objc_getAssociatedObject(self, kDDAssociatedStorageUserInfo);
}

@end

这会让你在任何NSOperation或它的子类上得到一个userInfo ...例如NSBlockOperation或AFHTTPRequestOperation

演示：

    //AFNetwork test
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.google.de"]]];
    operation.userInfo = @{@"url":operation.request.URL};
    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        NSLog(@"download of %@ completed. userinfo is %@", operation.request.URL, operation.userInfo);
        if(queue.operationCount==0)
            exit(1);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"download of %@ failed. userinfo is %@", operation.request.URL, operation.userInfo);
        if(queue.operationCount==0)
            exit(1);
    }];
    [queue addOperation:operation];