在 Objective-C 中,你可以定义块的输入和输出,存储方法中传入的其中一个块,然后在以后使用该块:
// 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);
});
...
}
所以我正在尝试用Swift实现相同的功能:
var completionHandler:(Float)->Void={}
init() {
locationManager = CLLocationManager()
region = CLBeaconRegion()
timer = NSTimer()
}
convenience init(region: CLBeaconRegion, handler:((Float)->Void)) {
self.init()
locationManager.delegate = self
self.region = region
completionHandler = handler
rangedBeacons = NSMutableArray()
}
编译器不喜欢completionHandler的声明。虽然我不怪它,但是我该如何在Swift中定义一个可以设置和后续使用的闭包呢?