TungVdMiichi

let totalLikes = items.reduce(0, {$0 + $1.numberOfLike})

TungVdMiichi

let totalLikes = items.reduce(into: 0) { (totalLikes, item) in
    totalLikes += item.numberOfLike
}

TungVdMiichi

var totalLikes = 0
for item in items {
    totalLikes += item.numberOfLike
}

// result: 60

TungVdMiichi

struct FeedItem {
    let title: String
    let thumbnailURL: URL?
    let isFavorite: Bool
    let numberOfLike: Int
}

let items = [FeedItem(title: "title", thumbnailURL: nil, isFavorite: false, numberOfLike: 10),
             FeedItem(title: "another title", thumbnailURL: URL(string: "http:b-url.com")!, isFavorite: false, numberOfLike: 20),
             FeedItem(title: "even another title", thumbnailURL: URL(string: "http:c-url.com")!, isFavorite: true, numberOfLike: 30),

TungVdMiichi

let favoriteItems = items.filter({$0.isFavorite})

TungVdMiichi

let favoriteItems = items.filter { (item) -> Bool in
    return item.isFavorite == true
}

TungVdMiichi

var favoriteItems = [FeedItem]()
for item in items {
    if item.isFavorite {
        favoriteItems.append(item)
    }
}

TungVdMiichi

struct FeedItem {
    let title: String
    let thumbnailURL: URL?
    let isFavorite: Bool
}

let items = [FeedItem(title: "title", thumbnailURL: nil, isFavorite: false),
             FeedItem(title: "another title", thumbnailURL: URL(string: "http:b-url.com")!, isFavorite: false),
             FeedItem(title: "even another title", thumbnailURL: URL(string: "http:c-url.com")!, isFavorite: true),
             FeedItem(title: "even another another title", thumbnailURL: URL(string: "http:d-url.com")!, isFavorite: true)]

TungVdMiichi

let urls = items.compactMap { $0.thumbnailURL }

TungVdMiichi

let urls = items.compactMap { (item) -> URL? in
    return item.thumbnailURL
}

// result: [http:b-url.com, http:c-url.com, http:d-url.com]