我的 objective-c 文件中有一个函数(比如 MyBlockExecutor 类):
+ (void) runBlockFromDictionary: (NSDictionary*) blocksDict andKey: (NSString*) key
{
if ( [blocksDict objectForKey: key] != nil )
{
((MyBlock)[blocksDict objectForKey: key])();
}
}
现在,我想从 Swift 调用这个函数。这是我的快速调用:
MyBlockExecutor.runBlock(from: [
"key1":{ ()->Void in
print("block for key1 called")
}
], andKey: "key1")
这会使我的应用程序崩溃。我在这一行收到 EXC_BAD_ACCESS 错误:
((MyBlock)[blocksDict objectForKey: key])();
不过,从 Objective-C 调用相同的函数工作得很好。另外,我将 MyBlock 定义为:
typedef void (^MyBlock)(); //defined in MyBlockExecutor.h file
我该如何解决?
编辑:我对 objective-c 函数的变化持开放态度,我只是需要以某种方式将闭包集合从 swift 传递到我的 objective-c 函数并运行该 block 。
您可以使用与 Swift blocks not working 中类似的方法: 用 @convention(block)
注释 block 使用 Objective-C block 调用约定,并(显式)强制转换在将其放入字典之前将其添加到 Bất kỳ đối tượng nào
中:
let myBlock: @convention(block) () -> Void = {
print("block for key1 called")
}
let dict = ["key1": myBlock as AnyObject]
MyBlockExecutor.runBlock(from: dict, andKey: "key1")
这在我的测试中按预期工作。
它也类似于奎因的“爱斯基摩人!”建议在 the Apple developer forum作为一种方法传递闭包(在 Swift 中定义)作为 Objective-C 兼容通过指针对象,只是我替换了 unsafeBitCast
通过更简单的作为 AnyObject
.
您也可以内联编写所有内容:
MyBlockExecutor.runBlock(from: ["key1": {
print("block for key1 called")
} as @convention(block) () -> Void as AnyObject
], andKey: "key1")
或者定义一个辅助函数:
func objcBlock(from block: @convention(block) () -> Void) -> AnyObject {
return block as AnyObject
}
MyBlockExecutor.runBlock(from: ["key1": objcBlock {
print("block for key1 called")
}], andKey: "key1")
Tôi là một lập trình viên xuất sắc, rất giỏi!