いいから `!` を使え！ / Shut up and use `!` !

Transcript

1. ͍͍͔Β!Λ࢖͑ʂ
   f o r : 6 . & . * T X J G U
   

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2. }
   var employedBy = "YUMEMI Inc."
   
   
   var job = "iOS Tech Lead"
   
   
   var favoriteLanguage = "Swift"
   
   
   var twitter = "@lovee"
   
   
   var qiita = "lovee"
   
   
   var github = "el-hoshino"
   
   
   var additionalInfo = """
   
   
   อޢͨ͠ೣ͕ͷൃ৘ظʹಥೖͯ݁͠ߏେม
   
   
   """
   final class Me: Developable, Talkable {
   

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3. 4XJGUͰ!࢖ͬͯ·͢ʁ
   

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4. ΋ͪΖΜBool൓సҎ֎Ͱ
   

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5. 4XJGUʹ͓͚Δ!ͷओͳ࢖͍ಓ˞
   w Optionalͷڧ੍6OXSBQʢ*60ؚΉʣ
   w ܕม׵ͷڧ੍μ΢ϯΩϟετas!
   
   
   w ྫ֎ॲཧͷڧ੍ྫ֎ແࢹtry!
   ˞#PPM൓సҎ֎
   

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6. ڞ௨఺ɿϓϩάϥϜ͕
   

   Ϋϥογϡ͢ΔϦεΫ͕͋Δ
   

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7. !Λ࢖Θͳ͍ํ͕҆શ
   本当にそうか？
   

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8. ͜ͷίʔυͬͯɺ҆શʁ
   func doSomething() {
   
   
   let image = UIImage(named: "ImageName") ?? UIImage()
   
   
   // do something with image
   
   
   }
   

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9. ͜ͷίʔυͬͯɺ҆શʁ
   func doSomething() {
   
   
   guard let appDelegate = UIApplication
   
   
   .shared.delegate as? AppDelegate else {
   
   
   return
   
   
   }
   
   
   // do something with appDelegate
   
   
   }
   

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10. ͜ͷίʔυͬͯɺ҆શʁ
    func doSomething(with data: Data) {
    
    
    do {
    
    
    let decoder = JSONDecoder()
    
    
    let response = try decoder.decode(Response.self, from: data)
    
    
    // do something with response
    
    
    } catch {
    
    
    debugPrint(error)
    
    
    return
    
    
    }
    
    
    }
    

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11. ΞϓϦ͕Ϋϥογϡ͠ͳ͍͔Βɺ
    

    ҆શɻ
    

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12. ΞϓϦ͕Ϋϥογϡ͠ͳ͍͔Βɺ
    

    ҆શʜͳͷ͔ʁ
    

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13. ͦ΋ͦ΋ɺ҆શͬͯɺͳʹʁ
    

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14. ੲɺ0CK$͔Β4XJGUʹҠߦͨ࣌͠ͷ࿩˞
    w αʔό͔Βը૾σʔλͱදࣔαΠζΛऔಘ͢Δॲཧ͕͋ͬͨ
    w αΠζσʔλ͸෯ߴͦ͞ΕͧΕ0CK$ͷίʔυͰintValueͰऔಘͯͨ͠
    w 4XJGUԽ͢Δͱ͖͸Կ΋ߟ͑ͣʹas? Int ?? 0Ͱॲཧͯͨ͠
    w ϦϦʔεޙɺҰ෦ͷը૾ͷΈΞεϖΫτൺ͕มΘͬͯ͠·ͬͨࣄ͕݅ൃੜ
    w ௐࠪͨ͠Βɺαʔό͔Βؼ͖ͬͯͨσʔλ͕ͳ͔ͥจࣈྻσʔλͩͬͨͨ
    Ίɺ0CK$͸ࣗಈม׵ͯ͘͠Ε͕ͨ4XJGU͸ܕʹݫ͍ͨ͠Ίࣗಈม׵ͯ͘͠
    Εͣɺ?? 0ʹΑͬͯ0͕୅ೖ͞Εͨ
    w ෯0ߴ͞0ͷ৔߹͸σϑΥϧταΠζͰදࣔ͢Δॲཧ͕͋ͬͨͨΊɺςε
    τσʔλͰಈ࡞֬ೝ͢Δͱ͖͸શ͘ؾ͔ͮͳ͔ͬͨ
    ˞࣮࿩Ͱ͢
    

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15. Ϋϥογϡ͸͠ͳ͔͕ͬͨɺ
    

    !Λආ͚Δ͋·Γɺ
    

    ٯʹόάͷൃݟΛ஗Βͤͨ
    

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16. ʮ҆શʯͳιʔείʔυ͸ɺ
    όάΛຊ൪ϦϦʔεલʹ
    

    ؾ͔ͮͤΔ΂͖ɻ
    

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17. ͜ͷίʔυͬͯɺ҆શʁ
    func doSomething() {
    
    
    let image = UIImage(named: "ImageName") ?? UIImage()
    
    
    // do something with image
    
    
    }
    

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18. ͜ͷίʔυͷํ͕ɺ҆શ
    func doSomething() {
    
    
    let image = UIImage(named: "ImageName")!
    
    
    // do something with image
    
    
    }
    όϯυϧʹೖͬͯͳ͍ͱ͍͚ͳ͍͸ͣͷ
    

    ը૾Ϧιʔε͔ͩΒɺ
    ສ͕Ұೖͬͯͳ͔ͬͨΒͦΕ͸όάͳͷͰ
    ಈ࡞֬ೝͰΫϥογϡͯ͘͠Εͨํ͕
    

    ؾ෇͖΍͍͢
    

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19. ͜ͷίʔυͬͯɺ҆શʁ
    func doSomething() {
    
    
    guard let appDelegate = UIApplication
    
    
    .shared.delegate as? AppDelegate else {
    
    
    return
    
    
    }
    
    
    // do something with appDelegate
    
    
    }
    

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20. ͜ͷίʔυͷํ͕ɺ҆શ
    func doSomething() {
    
    
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    
    
    // do something with appDelegate
    
    
    }
    ϓϩδΣΫτͷ࡞Γ͕
    

    ͜ͷΑ͏ʹͳͬͯΔ͸ͣͳͷͰɺ
    ສ͕Ұ͜ΕͰμ΢ϯΩϟετͰ͖ͳ͔ͬͨΒ
    ઈରϓϩάϥϜ͕Կ͔ؒҧͬͯΔ͸͔ͣͩΒɺ
    ಈ࡞֬ೝͰΫϥογϡͯ͘͠Εͨํ͕
    ؾ෇͖΍͍͢
    

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21. !Λ࢖͏΂͖ॴͰ࢖ͬͨํ͕ɺ
    όάͷૣظൃݟʹͭͳ͕Γɺ
    Ή͠Ζ҆қͳѲΓ௵͠ΑΓ҆શɻ
    

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22. ౰વɺཚ༻ͯ͠͸͍͚ͳ͍ɻ
    

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23. ͜ͷίʔυͬͯɺ҆શʁ
    func doSomething(with data: Data) {
    
    
    do {
    
    
    let decoder = JSONDecoder()
    
    
    let response = try decoder.decode(Response.self, from: data)
    
    
    // do something with response
    
    
    } catch {
    
    
    debugPrint(error)
    
    
    return
    
    
    }
    
    
    }
    

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24. ͜ͷίʔυͷํ͕ɺ҆શ
    func doSomething(with data: Data) {
    
    
    do {
    
    
    let decoder = JSONDecoder()
    
    
    let response = try decoder.decode(Response.self, from: data)
    
    
    // do something with response
    
    
    } catch {
    
    
    assertionFailure("\(error)")
    
    
    return
    
    
    }
    
    
    } ԾʹαʔόͷσʔλͱҰக͠ͳ͔ͬͨΒ
    BTTFSUJPO'BJMVSFʹΑͬͯ
    σόοάϏϧυ͚ͩΫϥογϡͯ͠
    

    όάΛૣظൃݟ͠ɺ
    ຊ൪ͷϦϦʔεϏϧυʹ͸Өڹͳ͠ɻ
    ʢ΋ͪΖΜ͜͜ͰߋʹΤϥʔΞϥʔτΛ
    

    Ϣʔβʹදࣔͤͨ͞Βͳ͓ྑ͠ʣ
    

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25. ͜ͷίʔυ͸ɺ͕͢͞ʹ҆શͰ͸ͳ͍
    func doSomething(with data: Data) {
    
    
    let decoder = JSONDecoder()
    
    
    let response = try! decoder.decode(Response.self, from: data)
    
    
    // do something with response
    
    
    }
    ສ͕Ұαʔόଆ͕όάΛى͜Γ
    

    ຊདྷͷ࢓༷ͱ͸ҧ͏ܕͷϨεϙϯε͕
    

    ؼ͖ͬͯͨΒ
    

    ΞϓϦ͕ଈΫϥογϡ͢ΔͷͰ
    

    ྲྀੴʹྑ͘ͳ͍
    

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26. 5*14ᶃ
    w ͦΕͰ΋΍͸ΓͲ͏ͯ͠΋ຊ൪ϦϦʔεͰΫϥογϡ
    ͯ͠ཉ͘͠ͳ͍ɻԿ͔ํ๏͋Δʁ
    w assertionFailureΛ࢖͑͹ɺσόοάϏϧυͩ
    ͚ΫϥογϡͰ͖ΔͷͰɺͥͻ׆༻͠·͠ΐ͏ɻ
    w ྫɿ
    let image = UIImage(named: "ImageName") ?? {
    
    
    assertionFailure("ImageName not found")
    
    
    return UIImage()
    
    
    }()
    

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27. 5*14ᶄ
    w ଞʹ΋Ͳ͔͜ੵۃతʹ!Λ࢖ͬͨํ͕৔໘͋Δʁ
    w ςετίʔυ΋Ή͠ΖੵۃతʹόάΛؾ෇͖͍ͨ͠
    ຊ൪ΞϓϦʹҰ੾Өڹ͠ͳ͍ͷͰɺੵۃతʹ!Λ࢖
    ͑Δ͜ͱ͕ଟ͍Ͱ͢ɻ
    w ͨͩ͠Ϋϥογϡ͢Δͱޙଓͷίʔυ΋ಈ͔ͳ͘
    ͳΔͷͰɺ৔ॴʹΑͬͯ͸XCTFailΛ࢖ͬͨํ
    ͕͍͍͜ͱ΋͋Γ·͢
    w 1MBZHSPVOEͱ͔ͷຊ൪ΞϓϦؔ܎ͳࣗ͘෼Ͱखܰ
    ͳಈ࡞֬ೝ͍ͨ࣌͠΋΋ͪΖΜੵۃతʹ࢖ͬͯΑ͠
    

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28. !Λա౓ʹڪΕͣʹ
    ͏·͘׆༻ͯ͠
    όάΛૣظʹ௵͠·͠ΐ͏
    

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