Arrays 缺少参数标签'；联合收割机：'；随时待命

获取如下所示的错误：

var products = [
    ("Kayak", "A boat for one person", "Watersports", 275.0, 10),
    ("Lifejacket", "Protective and fashionable", "Watersports", 48.95, 14)]

let stockTotal = products.reduce(0,{(total, product) -> Int in return total + product.4}); //missing argument label 'combine:' in call

在我看到的所有reduce示例中，未使用联合收割机标签：

let numbers = Array(1...10)
.reduce("numbers: ") {(total, number) in total + "\(number) "}

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那么我做错了什么呢？

使用尾随闭包语法：

let stockTotal = products.reduce(0) {(total, product) -> Int in return total + product.4}

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使用尾随闭包语法：

let stockTotal = products.reduce(0) {(total, product) -> Int in return total + product.4}

---

如果使用尾随闭包，则可以忽略标签：

var products = [
    ("Kayak", "A boat for one person", "Watersports", 275.0, 10),
    ("Lifejacket", "Protective and fashionable", "Watersports", 48.95, 14)
]

let stockTotal = products.reduce(0) { $0 + $1.4 }

对于尾随闭包，闭包将在最终的

）

之后提供给函数。如果不想使用尾随闭包，则需要添加参数标签：

let stockTotal2 = products.reduce(0, combine: { $0 + $1.4 })

---

如果使用尾随闭包，则可以忽略标签：

var products = [
    ("Kayak", "A boat for one person", "Watersports", 275.0, 10),
    ("Lifejacket", "Protective and fashionable", "Watersports", 48.95, 14)
]

let stockTotal = products.reduce(0) { $0 + $1.4 }

对于尾随闭包，闭包将在最终的

）

之后提供给函数。如果不想使用尾随闭包，则需要添加参数标签：

let stockTotal2 = products.reduce(0, combine: { $0 + $1.4 })

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