Swift - 如何从 HealthKit 类返回值

如何解决Swift - 如何从 HealthKit 类返回值

我是一个完整的初学者，只是在玩 HealthKit。也许你可以为我回答以下问题：

我有以下两个类：

//UIViewController

class ViewController: UIViewController {

@IBOutlet weak var BloodPressure: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()
    
    HealthControlAccess()
    
    let healthValue = HealthValue()
    healthValue.bloodPressureDiastolic()
    print (healthValue.averageDiastolic)

   }
}

//健康值

class HealthValue {

var averageDiastolic = 0

func bloodPressureDiastolic() {
    
    print ("bloodPressureDiastolic")
    
    let store = HKHealthStore()
    
    guard let bloodPressureDiastolic = HKObjectType.quantityType(forIdentifier: .bloodPressureDiastolic) else {
        // This should never fail when using a defined constant.
        fatalError("*** Unable to get the step count type ***")
    }
    
    let query = HKSampleQuery(sampleType: bloodPressureDiastolic,predicate: nil,limit: Int(HKObjectQueryNoLimit),sortDescriptors: nil) {
        
        query,results,error in
        
        guard let samples = results as? [HKQuantitySample] else {
            // Handle any errors here.
            return
        }
        
        var pressureDiastolic : String
        var pressureDiastolicArray : [Int] = Array()

        for sample in samples {

            pressureDiastolic = "\(sample.quantity)"
            pressureDiastolicArray.append(Int(pressureDiastolic.split(separator: " ")[0])!)
        }

        if pressureDiastolicArray.count > 0 {

            self.averageDiastolic = pressureDiastolicArray.sum()/pressureDiastolicArray.count

        }

    }

    store.execute(query)
    
}

我通过 ViewController 初始化 HealthValue 类，但我没有变量 healthValue.averageDiastolic 输出的值。

我做错了什么？

解决方法

HKSampleQuery 是异步的。您需要等待它完成才能访问结果。通常这是通过完成处理程序完成的：

func bloodPressureDiastolic(completion: (Double) -> Void) {

    ... Current code ...

    let query = HKSampleQuery(sampleType: bloodPressureDiastolic,predicate: nil,limit: Int(HKObjectQueryNoLimit),sortDescriptors: nil) {

        ... Current code ...

        if pressureDiastolicArray.count > 0 {
            self.averageDiastolic = pressureDiastolicArray.sum()/pressureDiastolicArray.count
        }

        Dispatch.main.async { [averageDiastolic] in
            completion(averageDiastolic) // <===
        }
    }

    store.execute(query)
}

然后你会这样称呼它：

class ViewController: UIViewController {

    @IBOutlet weak var BloodPressure: UILabel!

    let healthValue = HealthValue()

    override func viewDidLoad() {
        super.viewDidLoad()
    
        HealthControlAccess() // Not sure what this is doing. May need to wait for it to complete
    
        healthValue.bloodPressureDiastolic {
            print($0)
        }
    }
}