Swift - How to mutate a struct object when iterating over it

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清歌不尽
清歌不尽 2020-12-06 04:04

I am still not sure about the rules of struct copy or reference.

I want to mutate a struct object while iterating on it from an array: For instance in this case I wo

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  •  误落风尘
    2020-12-06 04:46

    struct are value types, thus in the for loop you are dealing with a copy.

    Just as a test you might try this:

    Swift 3:

    struct Options {
       var backgroundColor = UIColor.black
    }
    
    var arrayOfMyStruct = [Options]()
    
    for (index, _) in arrayOfMyStruct.enumerated() {
       arrayOfMyStruct[index].backgroundColor = UIColor.red
    }
    

    Swift 2:

    struct Options {
        var backgroundColor = UIColor.blackColor()
    }
    
    var arrayOfMyStruct = [Options]()
    
    for (index, _) in enumerate(arrayOfMyStruct) {
        arrayOfMyStruct[index].backgroundColor = UIColor.redColor() 
    }
    

    Here you just enumerate the index, and access directly the value stored in the array.

    Hope this helps.

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