我在Swift中做错了什么调用这个Objective-C块/ API调用？ [英] What am I doing wrong in Swift for calling this Objective-C block/API call?

问题描述

我使用 RedditKit 将Reddit集成到一个应用程序中，而在Objective-C中，我将API如下（并且工作正常）：

  [[RKClient sharedClient] signInWithUsername：@usernamepassword：@password completion：^（NSError * error）{
 RKPagination * pagination = [RKPagination paginationWithLimit：100]; 
 [[RKClient sharedClient] linksInSubredditWithName：subredditSelected分页：分页完成：^（NSArray * collection，RKPagination * pagination，NSError * error）{
 //完成时执行的代码
} 
}]; 
  

以下是我在Swift中调用它的方法：

pre> RKClient.sharedClient（）。signInWithUsername（username，password：password，completion：{（error：NSError！）in
RKClient.sharedClient .frontPageLinksWithPagination（RKPagination（limit：50），completion：{（collection：RKLink [] !, pagination：RKPagination !, error：NSError！）in
//代码执行完成
}）
}）


但是我一直收到这个错误的Swift版本：

无法找到接受所提供参数的'init'重载

EDIT：以下是一个示例项目： http://cl.ly/3K0i2P1r3j1y

解决方案

注意：此问题与以下问题相同：

animateWithDuration：animations：completion：in Swift

在dispatch_async中正确引用self

---

感谢您添加示例项目，问题如下：

从Swift书： https：/ /developer.apple.com/library/prerelease/ios/documentation/swift/conceptual/swift_programming_language/Closures.html

Closures的优化之一是：

单一表达式闭包的隐式回报

所以...编译器认为你的闭包是返回一个值 NSURLSessionDataTask ，因为它是闭包块内的唯一一行，从而改变了参数的类型。

有几种方法可以解决这个问题，没有一个是理想的...

你添加到闭包中的任何其他行将修复它，所以这将工作：

  RKClient.sharedClient（）。signInWithUsername username，password：password，completion：{error  - > （）in 
 let a = 1 
 RKClient.sharedClient（）。frontPageLinksWithPagination（nil，completion：nil）
}）
  

一个更简洁的解决方法是：

  RKClient。 sharedClient（）。signInWithUsername（username，password：password，completion：{in 
 let client = RKClient.sharedClient（）
 client.frontPageLinksWithPagination（nil，completion：nil）
}）
  

这不会是一个问题，如果你只是有更多的代码，以及！

I'm using RedditKit to integrate Reddit into an app, and in Objective-C I called the API as follows (and it worked fine):

    [[RKClient sharedClient] signInWithUsername:@"username" password:@"password" completion:^(NSError *error) {
        RKPagination *pagination = [RKPagination paginationWithLimit:100];
        [[RKClient sharedClient] linksInSubredditWithName:subredditSelected pagination:pagination completion:^(NSArray *collection, RKPagination *pagination, NSError *error) {
             // code that executes on completion
        }];
    }];

Here's how I'm calling it in Swift:

RKClient.sharedClient().signInWithUsername("username", password: "password", completion: { (error: NSError!) in
    RKClient.sharedClient().frontPageLinksWithPagination(RKPagination(limit: 50), completion: { (collection: RKLink[]!, pagination: RKPagination!, error: NSError!) in
        // code that executes on completion
    })
})

But I keep getting this error with the Swift version:

Could not find an overload for 'init' that accepts the supplied arguments

EDIT: Here's an example project showing it: http://cl.ly/3K0i2P1r3j1y

解决方案

Note: This issue is the same as in these questions:

animateWithDuration:animations:completion: in Swift

Properly referencing self in dispatch_async

---

Thanks for adding the example project, the issue is as follows:

From the Swift book: https://developer.apple.com/library/prerelease/ios/documentation/swift/conceptual/swift_programming_language/Closures.html

One of the optimizations of Closures is:

Implicit returns from single-expression closures

So... the compiler thinks your closure is returning a value of NSURLSessionDataTask because it is the only line inside the closure block, thus changing the type of the argument.

There are a few ways to solve this, none that are ideal...

The idea is that any other line you add into the closure will fix it, so this will literally work:

      RKClient.sharedClient().signInWithUsername("username", password: "password", completion: { error -> () in
            let a = 1
            RKClient.sharedClient().frontPageLinksWithPagination(nil, completion: nil)
        })

A slightly cleaner way to solve this would be:

RKClient.sharedClient().signInWithUsername("username", password: "password", completion: { error in
    let client = RKClient.sharedClient()
    client.frontPageLinksWithPagination(nil, completion: nil)
})

This wouldn't be an issue if you simply had more code to put into that closure as well!

这篇关于我在Swift中做错了什么调用这个Objective-C块/ API调用？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！