相关疑难解决方法(0)

在Objective-C中,您可以定义块的输入和输出,存储传递给方法的其中一个块,然后再使用该块:

// in .h

    typedef void (^APLCalibrationProgressHandler)(float percentComplete);
    typedef void (^APLCalibrationCompletionHandler)(NSInteger measuredPower, NSError *error);

    // in .m

    @property (strong) APLCalibrationProgressHandler progressHandler;
    @property (strong) APLCalibrationCompletionHandler completionHandler;

    - (id)initWithRegion:(CLBeaconRegion *)region completionHandler:(APLCalibrationCompletionHandler)handler
    {
        self = [super init];
        if(self)
        {
            ...
            _completionHandler = [handler copy];
            ..
        }

        return self;
}

- (void)performCalibrationWithProgressHandler:(APLCalibrationProgressHandler)handler
{
    ...

            self.progressHandler = [handler copy];

     ...
            dispatch_async(dispatch_get_main_queue(), ^{
                _completionHandler(0, error);
            });
     ...
}

所以我试图在Swift中做等效的事情:

var completionHandler:(Float)->Void={}


init() {
    locationManager = CLLocationManager()
    region = CLBeaconRegion()
    timer = NSTimer()
}

convenience init(region: CLBeaconRegion, …

我们可以在Objective-C中声明如下所示的块.

typedef void (^CompletionBlock) (NSString* completionReason);

我试图在swift中做到这一点,它给出了错误.

func completionFunction(NSString* completionReason){ }
typealias CompletionBlock = completionFunction

错误:使用未声明的'completionFunction'

定义:

var completion: CompletionBlock = { }

这该怎么做？

更新:

根据@ jtbandes的回答,我可以创建具有多个参数的闭包

typealias CompletionBlock = ( completionName : NSString, flag : Int) -> ()

在 Objective-C 中，我使用了对现在必须转换为 Swift 的完成块的处理：

在DetailDisplayController.h

typedef void (^AddedCompletitionBlock)(BOOL saved, NSString *primarykey, NSUInteger recordCount);

@interface DetailDisplayController : UITableViewController

@property (nonatomic, copy) AddedCompletitionBlock completionBlock;
@property (strong, nonatomic) Details *detail;

在DetailDisplayController.m

- (void) saveClicked:(id)sender
{  
   // retrieve PK
   NSString *objectId = [[[_detail objectID] URIRepresentation] absoluteString];

   if (self.completionBlock != nil)
   {
       self.completionBlock(_rowChanged, objectId, [_fetchedResultsController.fetchedObjects count]);
   }

_rowChanged 和 _fetchedResultsController 是实例变量

在DetailViewController.m调用类中，使用了传递的块

- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
   if ([segue.identifier isEqualToString:@"DetailDisplay"])
   {
       DetailDisplayController *detailDisplayController = segue.destinationViewController; 
       ...
       detailDisplayController.completionBlock = ^(BOOL saved, …