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Keys of a Dictionary must be unique and of immutable data type such as Strings, Integers and tuples, but the key-values can be repeated and be of any type. Nested Dictionary: Nesting Dictionary means putting a dictionary inside another dictionary.
You can create a nested dictionary in Python by placing comma-separated dictionaries within curly braces {}. A Python nested dictionary allows you to store and access data using the key-value mapping structure within an existing dictionary.
Using the merge operator, we can combine dictionaries in a single line of code. We can also merge the dictionaries in-place by using the update operator (|=).
There is no add() , append() , or insert() method you can use to add an item to a dictionary in Python. Instead, you add an item to a dictionary by inserting a new index key into the dictionary, then assigning it a particular value.
You can define += operator for Dictionary, e.g.,
func += <K, V> (left: inout [K:V], right: [K:V]) {
for (k, v) in right {
left[k] = v
}
}
In Swift 4, one should use merging(_:uniquingKeysWith:):
let dictA = ["x" : 1, "y": 2, "z": 3]
let dictB = ["x" : 11, "y": 22, "w": 0]
let resultA = dictA.merging(dictB, uniquingKeysWith: { (first, _) in first })
let resultB = dictA.merging(dictB, uniquingKeysWith: { (_, last) in last })
print(resultA) // ["x": 1, "y": 2, "z": 3, "w": 0]
print(resultB) // ["x": 11, "y": 22, "z": 3, "w": 0]
How about
dict2.forEach { (k,v) in dict1[k] = v }
That adds all of dict2's keys and values into dict1.
Swift 4 provides merging(_:uniquingKeysWith:), so for your case:
let combinedDict = dict1.merging(dict2) { $1 }
The shorthand closure returns $1, therefore dict2's value will be used when there is a conflict with the keys.
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