如何在Swift中创建唯一对象列表的数组

A new Set data structure is included which provides a generic
collection of unique elements,with full value semantics. It bridges
with NSSet,providing functionality analogous to Array and Dictionary.

这里有一些简单的用法示例：

// Create set from array literal:
var set = Set([1,2,3,1])

// Add single elements:
set.insert(4)
set.insert(3)

// Add multiple elements:
set.unionInPlace([ 4,5,6 ])
// Swift 3: set.formUnion([ 4,6 ])

// Remove single element:
set.remove(2)

// Remove multiple elements:
set.subtractInPlace([ 6,7 ])
// Swift 3: set.subtract([ 6,7 ])

print(set) // [5,1,4]

// Test membership:
if set.contains(5) {
    print("yes")
}

但有更多的方法可用。

更新：集合现在也记录在Swift文档的“Collection Types”章节中。