ios - 带有成功和失败的 Swift 方法链
<p><p>我正在尝试在我的代码中为成功和失败调用实现方法链接，但我似乎无法真正调用 <code>onSuccess</code> 方法。</p>
<ol>
<li> ViewController 调用 <code>getProduct(_:)</code> 函数。</li>
<li><code>getProduct(_:)</code> 进行 API 调用，然后使用检索到的 json 调用 <code>storeProduct(_:)</code></li>
<li><code>storeProduct(_:)</code> 调用 <code>fetchProduct(_:)</code></li>
<li><code>fetchProduct(_:)</code> 调用 <code>doSuccess(_:)</code> 但这永远不会回到先前调用的 <code>onSuccess</code> 中。<</li>
</ol>
<p><strong>一些代码片段</strong></p>
<p><em>BSProductChainable.swift</em></p>
<pre><code>import Foundation
class BSProductChainable<SuccessParams, FailureParams> {
var successClosure: ((SuccessParams) -> ())? = nil
var failureClosure: ((FailureParams) -> ())? = nil
func onSuccess(closure: (SuccessParams) -> ()) -> BSProductChainable {
successClosure = closure
return self
}
func onFailure(closure: (FailureParams) -> ()) -> BSProductChainable {
failureClosure = closure
return self
}
func doSuccess(params: SuccessParams) {
if let closure = successClosure {
closure(params)
}
}
func doFailure(params: FailureParams) {
if let closure = failureClosure {
closure(params)
}
}
}
</code></pre>
<p><em>BSProductManagerSwift.swift</em></p>
<pre><code>class BSProductManagerSwift: NSObject {
typealias productResponseChain = BSProductChainable<Product, NSError?>
typealias productsResponseChain = BSProductChainable<, NSError?>
var serviceClient: BSNetworkingServiceClient!
var objectContext: NSManagedObjectContext!
var productChains: BSProductChainable<Product, NSError?>!
var productsChains: BSProductChainable<, NSError?>!
convenience init(serviceClient: BSNetworkingServiceClient) {
self.init()
self.serviceClient = serviceClient
self.objectContext = managedObjectContext
self.productChains = BSProductChainable<Product, NSError?>()
self.productsChains = BSProductChainable<, NSError?>()
}
func getProduct(ean: String) -> productResponseChain {
let urlString = BSConstants.BarcodeScanner.productEndpoint.stringByAppendingString(ean)
serviceClient.GET(urlString, failure: { (error) in
print("Could not get product")
}) { (response) in
if let json = response {
self.storeProduct(json).onSuccess({ (returedProduct) in
print("Stored product")
})
}
}
return productChains
}
func storeProduct(json: JSON) -> productResponseChain {
fetchProduct(json["ean"].stringValue).onSuccess { (returedProduct) in
self.productChains.doSuccess(returedProduct)
}
return productChains
}
func fetchProduct(ean: String) -> productResponseChain {
let fetchRequest = NSFetchRequest(entityName: "Product")
let predicateEAN = NSPredicate(format: "%K == %@", "ean", ean)
let predicateMarket = NSPredicate(format: "%K == %@", "market", BSCountryManager.sharedInstance().getCurrentCountry().market)
let predicateLocale = NSPredicate(format: "%K == %@", "locale", BSLocalizationManager.sharedManager().currentLocalization.localeIdentifier())
let predicateCurrency = NSPredicate(format: "%K == %@", "currency", BSLocalizationManager.sharedManager().currentLocalization.country.currencyIdentifierDMW)
let compoundPredicate = NSCompoundPredicate(andPredicateWithSubpredicates: )
fetchRequest.predicate = compoundPredicate
do {
let matchingProuducts = try objectContext.executeFetchRequest(fetchRequest)
if matchingProuducts.count == 0 {
print("No matching products found")
let entity = NSEntityDescription.entityForName("Product", inManagedObjectContext: objectContext)
productChains.doSuccess(Product(entity: entity!, insertIntoManagedObjectContext: objectContext))
} else {
print("Found matching product")
let d = matchingProuducts.first as! Product
productChains.doSuccess(d)
}
} catch let error as NSError {
print("Could not fetch \(error), \(error.userInfo)")
productChains.doFailure(error)
}
return productChains
}
</code></pre>
<p>我最初为每个函数初始化了可链接类，但这有其自身的问题，我认为(可能是错误的)我应该只初始化可链接类一次并传递它的引用。</p>
<p>关于我哪里出错/接下来我可以尝试什么的一些输入会很棒。</p></p>
<br><hr><h1><strong>Best Answer-推荐答案</ strong></h1><br>
<p><p>根据@john elements 的建议，我决定使用 <a href="http://github.com/mxcl/PromiseKit" rel="noreferrer noopener nofollow">PromiseKit</a> </p>
<p>这不需要太多的代码更改，下面是函数现在的样子(仍然需要做一些代码清理，但它可以工作!):</p>
<pre><code>func getProduct(ean: String) -> Promise<Product> {
return Promise { fullfill, reject in
let urlString = BSConstants.BarcodeScanner.productEndpoint.stringByAppendingString(ean)
serviceClient.GET(urlString, failure: { (error) in
reject(error!)
}) { (response) in
if let json = response {
self.storeProduct(json).then ({ returnedProduct in
print("We stored the product: \(returnedProduct.ean)")
fullfill(returnedProduct)
}).error { returnedError in
print("We had a problem storing the product: \(returnedError)")
}
}
}
}
}
func storeProduct(json: JSON) -> Promise<Product> {
return Promise { fullfill, reject in
fetchProduct(json["ean"].stringValue).then ({ returnedProduct in
var storedProduct: Product!
var isNewProduct = false
print("Fetched Product: \(returnedProduct.ean)")
isNewProduct = returnedProduct.valueForKey("ean") == nil
storedProduct = returnedProduct
storedProduct.setValue(json["name"].stringValue, forKey: "name")
storedProduct.setValue(json["ean"].stringValue, forKey: "ean")
storedProduct.setValue(json["image"].stringValue, forKey: "image")
storedProduct.setValue(json["price"].doubleValue, forKey: "price")
storedProduct.setValue(json["status"].intValue, forKey: "status")
storedProduct.setValue(json["pdp"].stringValue, forKey: "pdp")
storedProduct.setValue(BSCountryManager.sharedInstance().getCurrentCountry().market, forKey: "market")
storedProduct.setValue(BSLocalizationManager.sharedManager().currentLocalization.localeIdentifier(), forKey: "locale")
storedProduct.setValue(BSLocalizationManager.sharedManager().currentLocalization.country.currencyIdentifierDMW, forKey: "currency")
do {
try self.objectContext.save()
print("Stored Product: \(returnedProduct.ean)")
fullfill(returnedProduct)
if isNewProduct {
NSNotificationCenter.defaultCenter().postNotificationName("DidAddScanEntry", object: nil)
}
} catch let error as NSError {
print("Could not save \(error), \(error.userInfo)")
reject(error)
}
}).error { returnedError in
print("We had a problem fetching the product: \(returnedError)")
reject(returnedError)
}
}
}
func fetchProduct(ean: String) -> Promise<Product> {
return Promise { fullfill, reject in
let fetchRequest = NSFetchRequest(entityName: "Product")
let predicateEAN = NSPredicate(format: "%K == %@", "ean", ean)
let predicateMarket = NSPredicate(format: "%K == %@", "market", BSCountryManager.sharedInstance().getCurrentCountry().market)
let predicateLocale = NSPredicate(format: "%K == %@", "locale", BSLocalizationManager.sharedManager().currentLocalization.localeIdentifier())
let predicateCurrency = NSPredicate(format: "%K == %@", "currency", BSLocalizationManager.sharedManager().currentLocalization.country.currencyIdentifierDMW)
let compoundPredicate = NSCompoundPredicate(andPredicateWithSubpredicates: )
fetchRequest.predicate = compoundPredicate
do {
let matchingProuducts = try objectContext.executeFetchRequest(fetchRequest)
if matchingProuducts.count == 0 {
print("No matching products found")
let entity = NSEntityDescription.entityForName("Product", inManagedObjectContext: objectContext)
fullfill(Product(entity: entity!, insertIntoManagedObjectContext: objectContext))
} else {
print("Found matching product")
let d = matchingProuducts.first as! Product
fullfill(d)
}
} catch let error as NSError {
print("Could not fetch \(error), \(error.userInfo)")
reject(error)
}
}
}
</code></pre></p>
<p style="font-size: 20px;">关于ios - 带有成功和失败的 Swift 方法链，我们在Stack Overflow上找到一个类似的问题：
<a href="https://stackoverflow.com/questions/38832681/" rel="noreferrer noopener nofollow" style="color: red;">
https://stackoverflow.com/questions/38832681/
</a>
</p>
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