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• 甯搁噺鍜屽彉閲�/a>
• 澹版槑甯搁噺鍜屽彉閲�/a>
• 绫诲瀷鏍囨敞
• 甯搁噺鍜屽彉閲忕殑鍛藉悕
• 杈撳嚭甯搁噺鍜屽彉閲�/a>
• 娉ㄩ噴
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• 鏁存暟
• 鏁存暟鑼冨洿
• Int
• UInt
• 娴偣鏁�/a>
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• if 璇彞浠ュ強寮哄埗瑙ｆ瀽
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• 闅愬紡瑙ｆ瀽鍙�绫诲瀷
• 閿欒澶勭悊
• 鏂█

Swift 鏄竴闂ㄥ紑鍙�iOS, OS X 鍜�watchOS 搴旂敤鐨勬柊璇█銆傜劧鑰岋紝濡傛灉浣犳湁 C 鎴栬� Objective-C 寮�彂缁忛獙鐨勮瘽锛屼綘浼氬彂鐜�Swift 鐨勫緢澶氬唴瀹归兘鏄綘鐔熸倝鐨勩�

Swift 鍖呭惈浜�C 鍜�Objective-C 涓婃墍鏈夊熀纭�暟鎹被鍨嬶紝Int琛ㄧず鏁村瀷鍊硷紱Double鍜�code>Float琛ㄧず娴偣鍨嬪�锛�code>Bool鏄竷灏斿瀷鍊硷紱String鏄枃鏈瀷鏁版嵁銆係wift 杩樻彁渚涗簡涓変釜鍩烘湰鐨勯泦鍚堢被鍨嬶紝Array锛�code>Set鍜�code>Dictionary锛岃瑙�a href="http://www.swift51.com/swift2.1/chapter2/04_Collection_Types.html">闆嗗悎绫诲瀷銆�/p>

灏卞儚 C 璇█涓�牱锛孲wift 浣跨敤鍙橀噺鏉ヨ繘琛屽瓨鍌ㄥ苟閫氳繃鍙橀噺鍚嶆潵鍏宠仈鍊笺�鍦�Swift 涓紝骞挎硾鐨勪娇鐢ㄧ潃鍊间笉鍙彉鐨勫彉閲忥紝瀹冧滑灏辨槸甯搁噺锛岃�涓旀瘮 C 璇█鐨勫父閲忔洿寮哄ぇ銆傚湪 Swift 涓紝濡傛灉浣犺澶勭悊鐨勫�涓嶉渶瑕佹敼鍙橈紝閭ｄ娇鐢ㄥ父閲忓彲浠ヨ浣犵殑浠ｇ爜鏇村姞瀹夊叏骞朵笖鏇存竻鏅板湴琛ㄨ揪浣犵殑鎰忓浘銆�/p>

闄や簡鎴戜滑鐔熸倝鐨勭被鍨嬶紝Swift 杩樺鍔犱簡 Objective-C 涓病鏈夌殑楂橀樁鏁版嵁绫诲瀷姣斿鍏冪粍锛圱uple锛夈�鍏冪粍鍙互璁╀綘鍒涘缓鎴栬�浼犻�涓�粍鏁版嵁锛屾瘮濡備綔涓哄嚱鏁扮殑杩斿洖鍊兼椂锛屼綘鍙互鐢ㄤ竴涓厓缁勫彲浠ヨ繑鍥炲涓�銆�/p>

Swift 杩樺鍔犱簡鍙�锛圤ptional锛夌被鍨嬶紝鐢ㄤ簬澶勭悊鍊肩己澶辩殑鎯呭喌銆傚彲閫夎〃绀�ldquo;閭ｅ効鏈変竴涓�锛屽苟涓斿畠绛変簬 x ”鎴栬�“閭ｅ効娌℃湁鍊�rdquo;銆傚彲閫夋湁鐐瑰儚鍦�Objective-C 涓娇鐢�code>nil锛屼絾鏄畠鍙互鐢ㄥ湪浠讳綍绫诲瀷涓婏紝涓嶄粎浠呮槸绫汇�鍙�绫诲瀷姣�Objective-C 涓殑nil鎸囬拡鏇村姞瀹夊叏涔熸洿鍏疯〃鐜板姏锛屽畠鏄�Swift 璁稿寮哄ぇ鐗规�鐨勯噸瑕佺粍鎴愰儴鍒嗐�

Swift 鏄竴闂ㄧ被鍨嬪畨鍏ㄧ殑璇█锛屽彲閫夌被鍨嬪氨鏄竴涓緢濂界殑渚嬪瓙銆係wift 鍙互璁╀綘娓呮鍦扮煡閬撳�鐨勭被鍨嬨�濡傛灉浣犵殑浠ｇ爜鏈熸湜寰楀埌涓�釜String锛岀被鍨嬪畨鍏ㄤ細闃绘浣犱笉灏忓績浼犲叆涓�釜Int銆備綘鍙互鍦ㄥ紑鍙戦樁娈靛敖鏃╁彂鐜板苟淇閿欒銆�/p>

锛夊叧鑱旇捣鏉ャ�甯搁噺鐨勫�涓�棪璁惧畾灏变笉鑳芥敼鍙橈紝鑰屽彉閲忕殑鍊煎彲浠ラ殢鎰忔洿鏀广�

let maximumNumberOfLoginAttempts = 10 var currentLoginAttempt = 0

杩欎袱琛屼唬鐮佸彲浠ヨ鐞嗚В涓猴細

“澹版槑涓�釜鍚嶅瓧鏄�code>maximumNumberOfLoginAttempts鐨勬柊甯搁噺锛屽苟缁欏畠涓�釜鍊�code>10銆傜劧鍚庯紝澹版槑涓�釜鍚嶅瓧鏄�code>currentLoginAttempt鐨勫彉閲忓苟灏嗗畠鐨勫�鍒濆鍖栦负0銆�rdquo;

鍦ㄨ繖涓緥瀛愪腑锛屽厑璁哥殑鏈�ぇ灏濊瘯鐧诲綍娆℃暟琚０鏄庝负涓�釜甯搁噺锛屽洜涓鸿繖涓�涓嶄細鏀瑰彉銆傚綋鍓嶅皾璇曠櫥褰曟鏁拌澹版槑涓轰竴涓彉閲忥紝鍥犱负姣忔灏濊瘯鐧诲綍澶辫触鐨勬椂鍊欓兘闇�澧炲姞杩欎釜鍊笺�

浣犲彲浠ュ湪涓�涓０鏄庡涓父閲忔垨鑰呭涓彉閲忥紝鐢ㄩ�鍙烽殧寮�細

var x = 0.0, y = 0.0, z = 0.0 

娉ㄦ剰锛�br />濡傛灉浣犵殑浠ｇ爜涓湁涓嶉渶瑕佹敼鍙樼殑鍊硷紝璇蜂娇鐢�code>let鍏抽敭瀛楀皢瀹冨０鏄庝负甯搁噺銆傚彧灏嗛渶瑕佹敼鍙樼殑鍊煎０鏄庝负鍙橀噺銆�/p>

绫诲瀷鏍囨敞

褰撲綘澹版槑甯搁噺鎴栬�鍙橀噺鐨勬椂鍊欏彲浠ュ姞涓婄被鍨嬫爣娉紙type annotation锛夛紝璇存槑甯搁噺鎴栬�鍙橀噺涓瀛樺偍鐨勫�鐨勭被鍨嬨�濡傛灉瑕佹坊鍔犵被鍨嬫爣娉紝闇�鍦ㄥ父閲忔垨鑰呭彉閲忓悕鍚庨潰鍔犱笂涓�釜鍐掑彿鍜岀┖鏍硷紝鐒跺悗鍔犱笂绫诲瀷鍚嶇О銆�/p>

杩欎釜渚嬪瓙缁�code>welcomeMessage鍙橀噺娣诲姞浜嗙被鍨嬫爣娉紝琛ㄧず杩欎釜鍙橀噺鍙互瀛樺偍String绫诲瀷鐨勫�锛�/p>

var welcomeMessage: String 

澹版槑涓殑鍐掑彿浠ｈ〃鐫�ldquo;鏄�..绫诲瀷”锛屾墍浠ヨ繖琛屼唬鐮佸彲浠ヨ鐞嗚В涓猴細

“澹版槑涓�釜绫诲瀷涓�code>String锛屽悕瀛椾负welcomeMessage鐨勫彉閲忋�”

“绫诲瀷涓�code>String”鐨勬剰鎬濇槸“鍙互瀛樺偍浠绘剰String绫诲瀷鐨勫�銆�rdquo;

welcomeMessage鍙橀噺鐜板湪鍙互琚缃垚浠绘剰瀛楃涓诧細

welcomeMessage = "Hello" 

浣犲彲浠ュ湪涓�涓畾涔夊涓悓鏍风被鍨嬬殑鍙橀噺锛岀敤閫楀彿鍒嗗壊锛屽苟鍦ㄦ渶鍚庝竴涓彉閲忓悕涔嬪悗娣诲姞绫诲瀷鏍囨敞锛�/p>

var red, green, blue: Double 

娉ㄦ剰锛�br />涓�埇鏉ヨ浣犲緢灏戦渶瑕佸啓绫诲瀷鏍囨敞銆傚鏋滀綘鍦ㄥ０鏄庡父閲忔垨鑰呭彉閲忕殑鏃跺�璧嬩簡涓�釜鍒濆鍊硷紝Swift鍙互鎺ㄦ柇鍑鸿繖涓父閲忔垨鑰呭彉閲忕殑绫诲瀷锛岃鍙傝�绫诲瀷瀹夊叏鍜岀被鍨嬫帹鏂�/a>銆傚湪涓婇潰鐨勪緥瀛愪腑锛屾病鏈夌粰welcomeMessage璧嬪垵濮嬪�锛屾墍浠ュ彉閲�code>welcomeMessage鐨勭被鍨嬫槸閫氳繃涓�釜绫诲瀷鏍囨敞鎸囧畾鐨勶紝鑰屼笉鏄�杩囧垵濮嬪�鎺ㄦ柇鐨勩�

甯搁噺鍜屽彉閲忕殑鍛藉悕

浣犲彲浠ョ敤浠讳綍浣犲枩娆㈢殑瀛楃浣滀负甯搁噺鍜屽彉閲忓悕锛屽寘鎷�Unicode 瀛楃锛�/p>

let π = 3.14159 let 浣犲ソ = "浣犲ソ涓栫晫" let 馃惗馃惍 = "dogcow" 

甯搁噺涓庡彉閲忓悕涓嶈兘鍖呭惈鏁板绗﹀彿锛岀澶达紝淇濈暀鐨勶紙鎴栬�闈炴硶鐨勶級Unicode 鐮佷綅锛岃繛绾夸笌鍒惰〃绗︺�涔熶笉鑳戒互鏁板瓧寮�ご锛屼絾鏄彲浠ュ湪甯搁噺涓庡彉閲忓悕鐨勫叾浠栧湴鏂瑰寘鍚暟瀛椼�

涓�棪浣犲皢甯搁噺鎴栬�鍙橀噺澹版槑涓虹‘瀹氱殑绫诲瀷锛屼綘灏变笉鑳戒娇鐢ㄧ浉鍚岀殑鍚嶅瓧鍐嶆杩涜澹版槑锛屾垨鑰呮敼鍙樺叾瀛樺偍鐨勫�鐨勭被鍨嬨�鍚屾椂锛屼綘涔熶笉鑳藉皢甯搁噺涓庡彉閲忚繘琛屼簰杞�

娉ㄦ剰锛�br />濡傛灉浣犻渶瑕佷娇鐢ㄤ笌Swift淇濈暀鍏抽敭瀛楃浉鍚岀殑鍚嶇О浣滀负甯搁噺鎴栬�鍙橀噺鍚嶏紝浣犲彲浠ヤ娇鐢ㄥ弽寮曞彿锛坄锛夊皢鍏抽敭瀛楀寘鍥寸殑鏂瑰紡灏嗗叾浣滀负鍚嶅瓧浣跨敤銆傛棤璁哄浣曪紝浣犲簲褰撻伩鍏嶄娇鐢ㄥ叧閿瓧浣滀负甯搁噺鎴栧彉閲忓悕锛岄櫎闈炰綘鍒棤閫夋嫨銆�/p>

浣犲彲浠ユ洿鏀圭幇鏈夌殑鍙橀噺鍊间负鍏朵粬鍚岀被鍨嬬殑鍊硷紝鍦ㄤ笅闈㈢殑渚嬪瓙涓紝friendlyWelcome鐨勫�浠�code>"Hello!"鏀逛负浜�code>"Bonjour!":

var friendlyWelcome = "Hello!" friendlyWelcome = "Bonjour!" // friendlyWelcome 鐜板湪鏄�"Bonjour!" 

涓庡彉閲忎笉鍚岋紝甯搁噺鐨勫�涓�棪琚‘瀹氬氨涓嶈兘鏇存敼浜嗐�灏濊瘯杩欐牱鍋氫細瀵艰嚧缂栬瘧鏃舵姤閿欙細

let languageName = "Swift" languageName = "Swift++" // 杩欎細鎶ョ紪璇戞椂閿欒 - languageName 涓嶅彲鏀瑰彉 

print(friendlyWelcome) // 杈撳嚭 "Bonjour!"

print(_:separator:terminator:)鏄竴涓敤鏉ヨ緭鍑轰竴涓垨澶氫釜鍊煎埌閫傚綋杈撳嚭鍖虹殑鍏ㄥ眬鍑芥暟銆傚鏋滀綘鐢�Xcode锛�code>print(_:separator:terminator:)灏嗕細杈撳嚭鍐呭鍒�ldquo;console”闈㈡澘涓娿�separator鍜�code>terminator鍙傛暟鍏锋湁榛樿鍊硷紝鍥犳浣犺皟鐢ㄨ繖涓嚱鏁扮殑鏃跺�鍙互蹇界暐瀹冧滑銆傞粯璁ゆ儏鍐典笅锛岃鍑芥暟閫氳繃娣诲姞鎹㈣绗︽潵缁撴潫褰撳墠琛屻�濡傛灉涓嶆兂鎹㈣锛屽彲浠ヤ紶閫掍竴涓┖瀛楃涓茬粰terminator鍙傛暟--渚嬪锛�code>print(someValue, terminator:"")銆傚叧浜庡弬鏁伴粯璁ゅ�鐨勬洿澶氫俊鎭紝璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/06_Functions.html#default_parameter_values">榛樿鍙傛暟鍊�/a>銆�/p>

Swift 鐢ㄥ瓧绗︿覆鎻掑�锛坰tring interpolation锛夌殑鏂瑰紡鎶婂父閲忓悕鎴栬�鍙橀噺鍚嶅綋鍋氬崰浣嶇鍔犲叆鍒伴暱瀛楃涓蹭腑锛孲wift 浼氱敤褰撳墠甯搁噺鎴栧彉閲忕殑鍊兼浛鎹㈣繖浜涘崰浣嶇銆傚皢甯搁噺鎴栧彉閲忓悕鏀惧叆鍦嗘嫭鍙蜂腑锛屽苟鍦ㄥ紑鎷彿鍓嶄娇鐢ㄥ弽鏂滄潬灏嗗叾杞箟锛�/p>

print("The current value of friendlyWelcome is \(friendlyWelcome)") // 杈撳嚭 "The current value of friendlyWelcome is Bonjour! 

娉ㄦ剰锛�br />瀛楃涓叉彃鍊兼墍鏈夊彲鐢ㄧ殑閫夐」锛岃鍙傝�瀛楃涓叉彃鍊�/a>銆�/p>

娉ㄩ噴

璇峰皢浣犵殑浠ｇ爜涓殑闈炴墽琛屾枃鏈敞閲婃垚鎻愮ず鎴栬�绗旇浠ユ柟渚夸綘灏嗘潵闃呰銆係wift 鐨勭紪璇戝櫒灏嗕細鍦ㄧ紪璇戜唬鐮佹椂鑷姩蹇界暐鎺夋敞閲婇儴鍒嗐�

Swift 涓殑娉ㄩ噴涓�C 璇█鐨勬敞閲婇潪甯哥浉浼笺�鍗曡娉ㄩ噴浠ュ弻姝ｆ枩鏉狅紙//锛変綔涓鸿捣濮嬫爣璁�

// 杩欐槸涓�釜娉ㄩ噴 

浣犱篃鍙互杩涜澶氳娉ㄩ噴锛屽叾璧峰鏍囪涓哄崟涓鏂滄潬鍚庤窡闅忎竴涓槦鍙凤紙/*锛夛紝缁堟鏍囪涓轰竴涓槦鍙峰悗璺熼殢鍗曚釜姝ｆ枩鏉狅紙*/锛�

/* 杩欐槸涓�釜, 澶氳娉ㄩ噴 */ 

涓�C 璇█澶氳娉ㄩ噴涓嶅悓锛孲wift 鐨勫琛屾敞閲婂彲浠ュ祵濂楀湪鍏跺畠鐨勫琛屾敞閲婁箣涓�浣犲彲浠ュ厛鐢熸垚涓�釜澶氳娉ㄩ噴鍧楋紝鐒跺悗鍦ㄨ繖涓敞閲婂潡涔嬩腑鍐嶅祵濂楁垚绗簩涓琛屾敞閲娿�缁堟娉ㄩ噴鏃跺厛鎻掑叆绗簩涓敞閲婂潡鐨勭粓姝㈡爣璁帮紝鐒跺悗鍐嶆彃鍏ョ涓�釜娉ㄩ噴鍧楃殑缁堟鏍囪锛�/p>

/* 杩欐槸绗竴涓琛屾敞閲婄殑寮�ご /* 杩欐槸绗簩涓宓屽鐨勫琛屾敞閲�*/ 杩欐槸绗竴涓琛屾敞閲婄殑缁撳熬 */ 

閫氳繃杩愮敤宓屽澶氳娉ㄩ噴锛屼綘鍙互蹇�鏂逛究鐨勬敞閲婃帀涓�ぇ娈典唬鐮侊紝鍗充娇杩欐浠ｇ爜涔嬩腑宸茬粡鍚湁浜嗗琛屾敞閲婂潡銆�/p>

鍒嗗彿

涓庡叾浠栧ぇ閮ㄥ垎缂栫▼璇█涓嶅悓锛孲wift 骞朵笉寮哄埗瑕佹眰浣犲湪姣忔潯璇彞鐨勭粨灏惧浣跨敤鍒嗗彿锛�code>;锛夛紝褰撶劧锛屼綘涔熷彲浠ユ寜鐓т綘鑷繁鐨勪範鎯坊鍔犲垎鍙枫�鏈変竴绉嶆儏鍐典笅蹇呴』瑕佺敤鍒嗗彿锛屽嵆浣犳墦绠楀湪鍚屼竴琛屽唴鍐欏鏉＄嫭绔嬬殑璇彞锛�/p>

let cat = "馃惐"; print(cat) // 杈撳嚭 "馃惐" 

鏁存暟

鏁存暟灏辨槸娌℃湁灏忔暟閮ㄥ垎鐨勬暟瀛楋紝姣斿42鍜�code>-23銆傛暣鏁板彲浠ユ槸鏈夌鍙�/code>锛堟銆佽礋銆侀浂锛夋垨鑰�code>鏃犵鍙�/code>锛堟銆侀浂锛夈�

Swift 鎻愪緵浜�锛�6锛�2鍜�4浣嶇殑鏈夌鍙峰拰鏃犵鍙锋暣鏁扮被鍨嬨�杩欎簺鏁存暟绫诲瀷鍜�C 璇█鐨勫懡鍚嶆柟寮忓緢鍍忥紝姣斿8浣嶆棤绗﹀彿鏁存暟绫诲瀷鏄�code>UInt8锛�2浣嶆湁绗﹀彿鏁存暟绫诲瀷鏄�code>Int32銆傚氨鍍�Swift 鐨勫叾浠栫被鍨嬩竴鏍凤紝鏁存暟绫诲瀷閲囩敤澶у啓鍛藉悕娉曘�

鏁存暟鑼冨洿

浣犲彲浠ヨ闂笉鍚屾暣鏁扮被鍨嬬殑min鍜�code>max灞炴�鏉ヨ幏鍙栧搴旂被鍨嬬殑鏈�皬鍊煎拰鏈�ぇ鍊硷細

let minValue = UInt8.min // minValue 涓�0锛屾槸 UInt8 绫诲瀷 let maxValue = UInt8.max // maxValue 涓�255锛屾槸 UInt8 绫诲瀷 

min鍜�code>max鎵�紶鍥炲�鐨勭被鍨嬶紝姝ｆ槸鍏舵墍瀵圭殑鏁存暟绫诲瀷(濡備笂渚婾Int8, 鎵�紶鍥炵殑绫诲瀷鏄疷Int8)锛屽彲鐢ㄥ湪琛ㄨ揪寮忎腑鐩稿悓绫诲瀷鍊兼梺銆�/p>

Int

涓�埇鏉ヨ锛屼綘涓嶉渶瑕佷笓闂ㄦ寚瀹氭暣鏁扮殑闀垮害銆係wift 鎻愪緵浜嗕竴涓壒娈婄殑鏁存暟绫诲瀷Int锛岄暱搴︿笌褰撳墠骞冲彴鐨勫師鐢熷瓧闀跨浉鍚岋細

• 鍦�2浣嶅钩鍙颁笂锛�code>Int鍜�code>Int32闀垮害鐩稿悓銆�/li>
• 鍦�4浣嶅钩鍙颁笂锛�code>Int鍜�code>Int64闀垮害鐩稿悓銆�/li>

闄ら潪浣犻渶瑕佺壒瀹氶暱搴︾殑鏁存暟锛屼竴鑸潵璇翠娇鐢�code>Int灏卞浜嗐�杩欏彲浠ユ彁楂樹唬鐮佷竴鑷存�鍜屽彲澶嶇敤鎬с�鍗充娇鏄湪32浣嶅钩鍙颁笂锛�code>Int鍙互瀛樺偍鐨勬暣鏁拌寖鍥翠篃鍙互杈惧埌-2,147,483,648~2,147,483,647锛屽ぇ澶氭暟鏃跺�杩欏凡缁忚冻澶熷ぇ浜嗐�

UInt

Swift 涔熸彁渚涗簡涓�釜鐗规畩鐨勬棤绗﹀彿绫诲瀷UInt锛岄暱搴︿笌褰撳墠骞冲彴鐨勫師鐢熷瓧闀跨浉鍚岋細

• 鍦�2浣嶅钩鍙颁笂锛�code>UInt鍜�code>UInt32闀垮害鐩稿悓銆�/li>
• 鍦�4浣嶅钩鍙颁笂锛�code>UInt鍜�code>UInt64闀垮害鐩稿悓銆�/li>

娉ㄦ剰锛�br />灏介噺涓嶈浣跨敤UInt锛岄櫎闈炰綘鐪熺殑闇�瀛樺偍涓�釜鍜屽綋鍓嶅钩鍙板師鐢熷瓧闀跨浉鍚岀殑鏃犵鍙锋暣鏁般�闄や簡杩欑鎯呭喌锛屾渶濂戒娇鐢�code>Int锛屽嵆浣夸綘瑕佸瓨鍌ㄧ殑鍊煎凡鐭ユ槸闈炶礋鐨勩�缁熶竴浣跨敤Int鍙互鎻愰珮浠ｇ爜鐨勫彲澶嶇敤鎬э紝閬垮厤涓嶅悓绫诲瀷鏁板瓧涔嬮棿鐨勮浆鎹紝骞朵笖鍖归厤鏁板瓧鐨勭被鍨嬫帹鏂紝璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/01_The_Basics.html#type_safety_and_type_inference">绫诲瀷瀹夊叏鍜岀被鍨嬫帹鏂�/a>銆�/p>

let meaningOfLife = 42 // meaningOfLife 浼氳鎺ㄦ祴涓�Int 绫诲瀷

鍚岀悊锛屽鏋滀綘娌℃湁缁欐诞鐐瑰瓧闈㈤噺鏍囨槑绫诲瀷锛孲wift 浼氭帹鏂綘鎯宠鐨勬槸Double锛�/p>

let pi = 3.14159 // pi 浼氳鎺ㄦ祴涓�Double 绫诲瀷 

褰撴帹鏂诞鐐规暟鐨勭被鍨嬫椂锛孲wift 鎬绘槸浼氶�鎷�code>Double鑰屼笉鏄�code>Float銆�/p>

濡傛灉琛ㄨ揪寮忎腑鍚屾椂鍑虹幇浜嗘暣鏁板拰娴偣鏁帮紝浼氳鎺ㄦ柇涓�code>Double绫诲瀷锛�/p>

let anotherPi = 3 + 0.14159 // anotherPi 浼氳鎺ㄦ祴涓�Double 绫诲瀷 

鍘熷鍊�code>3娌℃湁鏄惧紡澹版槑绫诲瀷锛岃�琛ㄨ揪寮忎腑鍑虹幇浜嗕竴涓诞鐐瑰瓧闈㈤噺锛屾墍浠ヨ〃杈惧紡浼氳鎺ㄦ柇涓�code>Double绫诲瀷銆�/p>

鏁板�鍨嬪瓧闈㈤噺

鏁存暟瀛楅潰閲忓彲浠ヨ鍐欎綔锛�/p>

• 涓�釜鍗佽繘鍒�/em>鏁帮紝娌℃湁鍓嶇紑
• 涓�釜浜岃繘鍒�/em>鏁帮紝鍓嶇紑鏄�code>0b
• 涓�釜鍏繘鍒�/em>鏁帮紝鍓嶇紑鏄�code>0o
• 涓�釜鍗佸叚杩涘埗鏁帮紝鍓嶇紑鏄�code>0x

涓嬮潰鐨勬墍鏈夋暣鏁板瓧闈㈤噺鐨勫崄杩涘埗鍊奸兘鏄�code>17:

let decimalInteger = 17 let binaryInteger = 0b10001 // 浜岃繘鍒剁殑17 let octalInteger = 0o21 // 鍏繘鍒剁殑17 let hexadecimalInteger = 0x11 // 鍗佸叚杩涘埗鐨�7 

娴偣瀛楅潰閲忓彲浠ユ槸鍗佽繘鍒讹紙娌℃湁鍓嶇紑锛夋垨鑰呮槸鍗佸叚杩涘埗锛堝墠缂�槸0x锛夈�灏忔暟鐐逛袱杈瑰繀椤绘湁鑷冲皯涓�釜鍗佽繘鍒舵暟瀛楋紙鎴栬�鏄崄鍏繘鍒剁殑鏁板瓧锛夈�鍗佽繘鍒舵诞鐐规暟涔熷彲浠ユ湁涓�釜鍙�鐨勬寚鏁帮紙exponent)锛岄�杩囧ぇ鍐欐垨鑰呭皬鍐欑殑 e 鏉ユ寚瀹氾紱鍗佸叚杩涘埗娴偣鏁板繀椤绘湁涓�釜鎸囨暟锛岄�杩囧ぇ鍐欐垨鑰呭皬鍐欑殑 p 鏉ユ寚瀹氥�

濡傛灉涓�釜鍗佽繘鍒舵暟鐨勬寚鏁颁负exp锛岄偅杩欎釜鏁扮浉褰撲簬鍩烘暟鍜�0^exp鐨勪箻绉細

• 1.25e2 琛ㄧず 1.25 × 10^2锛岀瓑浜�nbsp;125.0銆�/li>
• 1.25e-2 琛ㄧず 1.25 × 10^-2锛岀瓑浜�nbsp;0.0125銆�/li>

濡傛灉涓�釜鍗佸叚杩涘埗鏁扮殑鎸囨暟涓�code>exp锛岄偅杩欎釜鏁扮浉褰撲簬鍩烘暟鍜�^exp鐨勪箻绉細

• 0xFp2 琛ㄧず 15 × 2^2锛岀瓑浜�nbsp;60.0銆�/li>
• 0xFp-2 琛ㄧず 15 × 2^-2锛岀瓑浜�nbsp;3.75銆�/li>

涓嬮潰鐨勮繖浜涙诞鐐瑰瓧闈㈤噺閮界瓑浜庡崄杩涘埗鐨�code>12.1875锛�/p>

let decimalDouble = 12.1875 let exponentDouble = 1.21875e1 let hexadecimalDouble = 0xC.3p0 

鏁板�绫诲瓧闈㈤噺鍙互鍖呮嫭棰濆鐨勬牸寮忔潵澧炲己鍙鎬с�鏁存暟鍜屾诞鐐规暟閮藉彲浠ユ坊鍔犻澶栫殑闆跺苟涓斿寘鍚笅鍒掔嚎锛屽苟涓嶄細褰卞搷瀛楅潰閲忥細

let paddedDouble = 000123.456 let oneMillion = 1_000_000 let justOverOneMillion = 1_000_000.000_000_1 

鏁存暟杞崲

涓嶅悓鏁存暟绫诲瀷鐨勫彉閲忓拰甯搁噺鍙互瀛樺偍涓嶅悓鑼冨洿鐨勬暟瀛椼�Int8绫诲瀷鐨勫父閲忔垨鑰呭彉閲忓彲浠ュ瓨鍌ㄧ殑鏁板瓧鑼冨洿鏄�code>-128~127锛岃�UInt8绫诲瀷鐨勫父閲忔垨鑰呭彉閲忚兘瀛樺偍鐨勬暟瀛楄寖鍥存槸0~255銆傚鏋滄暟瀛楄秴鍑轰簡甯搁噺鎴栬�鍙橀噺鍙瓨鍌ㄧ殑鑼冨洿锛岀紪璇戠殑鏃跺�浼氭姤閿欙細

let cannotBeNegative: UInt8 = -1 // UInt8 绫诲瀷涓嶈兘瀛樺偍璐熸暟锛屾墍浠ヤ細鎶ラ敊 let tooBig: Int8 = Int8.max + 1 // Int8 绫诲瀷涓嶈兘瀛樺偍瓒呰繃鏈�ぇ鍊肩殑鏁帮紝鎵�互浼氭姤閿� 

鐢变簬姣忕鏁存暟绫诲瀷閮藉彲浠ュ瓨鍌ㄤ笉鍚岃寖鍥寸殑鍊硷紝鎵�互浣犲繀椤绘牴鎹笉鍚屾儏鍐甸�鎷╂�浣跨敤鏁板�鍨嬬被鍨嬭浆鎹€�杩欑閫夋嫨鎬т娇鐢ㄧ殑鏂瑰紡锛屽彲浠ラ闃查殣寮忚浆鎹㈢殑閿欒骞惰浣犵殑浠ｇ爜涓殑绫诲瀷杞崲鎰忓浘鍙樺緱娓呮櫚銆�/p>

瑕佸皢涓�鏁板瓧绫诲瀷杞崲鎴愬彟涓�锛屼綘瑕佺敤褰撳墠鍊兼潵鍒濆鍖栦竴涓湡鏈涚被鍨嬬殑鏂版暟瀛楋紝杩欎釜鏁板瓧鐨勭被鍨嬪氨鏄綘鐨勭洰鏍囩被鍨嬨�鍦ㄤ笅闈㈢殑渚嬪瓙涓紝甯搁噺twoThousand鏄�code>UInt16绫诲瀷锛岀劧鑰屽父閲�code>one鏄�code>UInt8绫诲瀷銆傚畠浠笉鑳界洿鎺ョ浉鍔狅紝鍥犱负瀹冧滑绫诲瀷涓嶅悓銆傛墍浠ヨ璋冪敤UInt16(one)鏉ュ垱寤轰竴涓柊鐨�code>UInt16鏁板瓧骞剁敤one鐨勫�鏉ュ垵濮嬪寲锛岀劧鍚庝娇鐢ㄨ繖涓柊鏁板瓧鏉ヨ绠楋細

let twoThousand: UInt16 = 2_000 let one: UInt8 = 1 let twoThousandAndOne = twoThousand + UInt16(one) 

鐜板湪涓や釜鏁板瓧鐨勭被鍨嬮兘鏄�code>UInt16锛屽彲浠ヨ繘琛岀浉鍔犮�鐩爣甯搁噺twoThousandAndOne鐨勭被鍨嬭鎺ㄦ柇涓�code>UInt16锛屽洜涓哄畠鏄袱涓�code>UInt16鍊肩殑鍜屻�

SomeType(ofInitialValue)鏄皟鐢�Swift 鏋勯�鍣ㄥ苟浼犲叆涓�釜鍒濆鍊肩殑榛樿鏂规硶銆傚湪璇█鍐呴儴锛�code>UInt16鏈変竴涓瀯閫犲櫒锛屽彲浠ユ帴鍙椾竴涓�code>UInt8绫诲瀷鐨勫�锛屾墍浠ヨ繖涓瀯閫犲櫒鍙互鐢ㄧ幇鏈夌殑UInt8鏉ュ垱寤轰竴涓柊鐨�code>UInt16銆傛敞鎰忥紝浣犲苟涓嶈兘浼犲叆浠绘剰绫诲瀷鐨勫�锛屽彧鑳戒紶鍏�code>UInt16鍐呴儴鏈夊搴旀瀯閫犲櫒鐨勫�銆備笉杩囦綘鍙互鎵╁睍鐜版湁鐨勭被鍨嬫潵璁╁畠鍙互鎺ユ敹鍏朵粬绫诲瀷鐨勫�锛堝寘鎷嚜瀹氫箟绫诲瀷锛夛紝璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/20_Extensions.html">鎵╁睍銆�/p>

鏁存暟鍜屾诞鐐规暟杞崲

鏁存暟鍜屾诞鐐规暟鐨勮浆鎹㈠繀椤绘樉寮忔寚瀹氱被鍨嬶細

let three = 3 let pointOneFourOneFiveNine = 0.14159 let pi = Double(three) + pointOneFourOneFiveNine // pi 绛変簬 3.14159锛屾墍浠ヨ鎺ㄦ祴涓�Double 绫诲瀷 

杩欎釜渚嬪瓙涓紝甯搁噺three鐨勫�琚敤鏉ュ垱寤轰竴涓�code>Double绫诲瀷鐨勫�锛屾墍浠ュ姞鍙蜂袱杈圭殑鏁扮被鍨嬮』鐩稿悓銆傚鏋滀笉杩涜杞崲锛屼袱鑰呮棤娉曠浉鍔犮�

娴偣鏁板埌鏁存暟鐨勫弽鍚戣浆鎹㈠悓鏍疯锛屾暣鏁扮被鍨嬪彲浠ョ敤Double鎴栬�Float绫诲瀷鏉ュ垵濮嬪寲锛�/p>

let integerPi = Int(pi) // integerPi 绛変簬 3锛屾墍浠ヨ鎺ㄦ祴涓�Int 绫诲瀷 

褰撶敤杩欑鏂瑰紡鏉ュ垵濮嬪寲涓�釜鏂扮殑鏁存暟鍊兼椂锛屾诞鐐瑰�浼氳鎴柇銆備篃灏辨槸璇�code>4.75浼氬彉鎴�code>4锛�code>-3.9浼氬彉鎴�code>-3銆�/p>

娉ㄦ剰锛�br />缁撳悎鏁板瓧绫诲父閲忓拰鍙橀噺涓嶅悓浜庣粨鍚堟暟瀛楃被瀛楅潰閲忋�瀛楅潰閲�code>3鍙互鐩存帴鍜屽瓧闈㈤噺0.14159鐩稿姞锛屽洜涓烘暟瀛楀瓧闈㈤噺鏈韩娌℃湁鏄庣‘鐨勭被鍨嬨�瀹冧滑鐨勭被鍨嬪彧鍦ㄧ紪璇戝櫒闇�姹傚�鐨勬椂鍊欒鎺ㄦ祴銆�/p>

绫诲瀷鍒悕

绫诲瀷鍒悕锛坱ype aliases锛夊氨鏄粰鐜版湁绫诲瀷瀹氫箟鍙︿竴涓悕瀛椼�浣犲彲浠ヤ娇鐢�code>typealias鍏抽敭瀛楁潵瀹氫箟绫诲瀷鍒悕銆�/p>

褰撲綘鎯宠缁欑幇鏈夌被鍨嬭捣涓�釜鏇存湁鎰忎箟鐨勫悕瀛楁椂锛岀被鍨嬪埆鍚嶉潪甯告湁鐢ㄣ�鍋囪浣犳鍦ㄥ鐞嗙壒瀹氶暱搴︾殑澶栭儴璧勬簮鐨勬暟鎹細

typealias AudioSample = UInt16 

瀹氫箟浜嗕竴涓被鍨嬪埆鍚嶄箣鍚庯紝浣犲彲浠ュ湪浠讳綍浣跨敤鍘熷鍚嶇殑鍦版柟浣跨敤鍒悕锛�/p>

var maxAmplitudeFound = AudioSample.min // maxAmplitudeFound 鐜板湪鏄�0 

鏈緥涓紝AudioSample琚畾涔変负UInt16鐨勪竴涓埆鍚嶃�鍥犱负瀹冩槸鍒悕锛�code>AudioSample.min瀹為檯涓婃槸UInt16.min锛屾墍浠ヤ細缁�code>maxAmplitudeFound璧嬩竴涓垵鍊�code>0銆�/p>

let orangesAreOrange = true let turnipsAreDelicious = false

orangesAreOrange鍜�code>turnipsAreDelicious鐨勭被鍨嬩細琚帹鏂负Bool锛屽洜涓哄畠浠殑鍒濆�鏄竷灏斿瓧闈㈤噺銆傚氨鍍忎箣鍓嶆彁鍒扮殑Int鍜�code>Double涓�牱锛屽鏋滀綘鍒涘缓鍙橀噺鐨勬椂鍊欑粰瀹冧滑璧嬪�true鎴栬�false锛岄偅浣犱笉闇�灏嗗父閲忔垨鑰呭彉閲忓０鏄庝负Bool绫诲瀷銆傚垵濮嬪寲甯搁噺鎴栬�鍙橀噺鐨勬椂鍊欏鏋滄墍璧嬬殑鍊肩被鍨嬪凡鐭ワ紝灏卞彲浠ヨЕ鍙戠被鍨嬫帹鏂紝杩欒 Swift 浠ｇ爜鏇村姞绠�磥骞朵笖鍙鎬ф洿楂樸�

褰撲綘缂栧啓鏉′欢璇彞姣斿if璇彞鐨勬椂鍊欙紝甯冨皵鍊奸潪甯告湁鐢細

if turnipsAreDelicious { print("Mmm, tasty turnips!") } else { print("Eww, turnips are horrible.") } // 杈撳嚭 "Eww, turnips are horrible." 

鏉′欢璇彞锛屼緥濡�code>if锛岃鍙傝�鎺у埗娴�/a>銆�/p>

濡傛灉浣犲湪闇�浣跨敤Bool绫诲瀷鐨勫湴鏂逛娇鐢ㄤ簡闈炲竷灏斿�锛孲wift 鐨勭被鍨嬪畨鍏ㄦ満鍒朵細鎶ラ敊銆備笅闈㈢殑渚嬪瓙浼氭姤鍛婁竴涓紪璇戞椂閿欒锛�/p>

let i = 1 if i { // 杩欎釜渚嬪瓙涓嶄細閫氳繃缂栬瘧锛屼細鎶ラ敊 } 

鐒惰�锛屼笅闈㈢殑渚嬪瓙鏄悎娉曠殑锛�/p>

let i = 1 if i == 1 { // 杩欎釜渚嬪瓙浼氱紪璇戞垚鍔� } 

i == 1鐨勬瘮杈冪粨鏋滄槸Bool绫诲瀷锛屾墍浠ョ浜屼釜渚嬪瓙鍙互閫氳繃绫诲瀷妫�煡銆傜被浼�code>i == 1杩欐牱鐨勬瘮杈冿紝璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/05_Control_Flow.html">鍩烘湰鎿嶄綔绗�/a>銆�/p>

鍜�Swift 涓殑鍏朵粬绫诲瀷瀹夊叏鐨勪緥瀛愪竴鏍凤紝杩欎釜鏂规硶鍙互閬垮厤閿欒骞朵繚璇佽繖鍧椾唬鐮佺殑鎰忓浘鎬绘槸娓呮櫚鐨勩�

鍏冪粍

鍏冪粍锛坱uples锛�/em>鎶婂涓�缁勫悎鎴愪竴涓鍚堝�銆傚厓缁勫唴鐨勫�鍙互鏄换鎰忕被鍨嬶紝骞朵笉瑕佹眰鏄浉鍚岀被鍨嬨�

涓嬮潰杩欎釜渚嬪瓙涓紝(404, "Not Found")鏄竴涓弿杩�nbsp;HTTP 鐘舵�鐮侊紙HTTP status code锛�/em>鐨勫厓缁勩�HTTP 鐘舵�鐮佹槸褰撲綘璇锋眰缃戦〉鐨勬椂鍊�web 鏈嶅姟鍣ㄨ繑鍥炵殑涓�釜鐗规畩鍊笺�濡傛灉浣犺姹傜殑缃戦〉涓嶅瓨鍦ㄥ氨浼氳繑鍥炰竴涓�code>404 Not Found鐘舵�鐮併�

let http404Error = (404, "Not Found") // http404Error 鐨勭被鍨嬫槸 (Int, String)锛屽�鏄�(404, "Not Found") 

(404, "Not Found")鍏冪粍鎶婁竴涓�code>Int鍊煎拰涓�釜String鍊肩粍鍚堣捣鏉ヨ〃绀�HTTP 鐘舵�鐮佺殑涓や釜閮ㄥ垎锛氫竴涓暟瀛楀拰涓�釜浜虹被鍙鐨勬弿杩般�杩欎釜鍏冪粍鍙互琚弿杩颁负“涓�釜绫诲瀷涓�code>(Int, String)鐨勫厓缁�rdquo;銆�/p>

浣犲彲浠ユ妸浠绘剰椤哄簭鐨勭被鍨嬬粍鍚堟垚涓�釜鍏冪粍锛岃繖涓厓缁勫彲浠ュ寘鍚墍鏈夌被鍨嬨�鍙浣犳兂锛屼綘鍙互鍒涘缓涓�釜绫诲瀷涓�code>(Int, Int, Int)鎴栬�(String, Bool)鎴栬�鍏朵粬浠讳綍浣犳兂瑕佺殑缁勫悎鐨勫厓缁勩�

浣犲彲浠ュ皢涓�釜鍏冪粍鐨勫唴瀹瑰垎瑙ｏ紙decompose锛夋垚鍗曠嫭鐨勫父閲忓拰鍙橀噺锛岀劧鍚庝綘灏卞彲浠ユ甯镐娇鐢ㄥ畠浠簡锛�/p>

let (statusCode, statusMessage) = http404Error print("The status code is \(statusCode)") // 杈撳嚭 "The status code is 404" print("The status message is \(statusMessage)") // 杈撳嚭 "The status message is Not Found" 

濡傛灉浣犲彧闇�涓�儴鍒嗗厓缁勫�锛屽垎瑙ｇ殑鏃跺�鍙互鎶婅蹇界暐鐨勯儴鍒嗙敤涓嬪垝绾匡紙_锛夋爣璁帮細

let (justTheStatusCode, _) = http404Error print("The status code is \(justTheStatusCode)") // 杈撳嚭 "The status code is 404" 

姝ゅ锛屼綘杩樺彲浠ラ�杩囦笅鏍囨潵璁块棶鍏冪粍涓殑鍗曚釜鍏冪礌锛屼笅鏍囦粠闆跺紑濮嬶細

print("The status code is \(http404Error.0)") // 杈撳嚭 "The status code is 404" print("The status message is \(http404Error.1)") // 杈撳嚭 "The status message is Not Found" 

浣犲彲浠ュ湪瀹氫箟鍏冪粍鐨勬椂鍊欑粰鍗曚釜鍏冪礌鍛藉悕锛�/p>

let http200Status = (statusCode: 200, description: "OK") 

缁欏厓缁勪腑鐨勫厓绱犲懡鍚嶅悗锛屼綘鍙互閫氳繃鍚嶅瓧鏉ヨ幏鍙栬繖浜涘厓绱犵殑鍊硷細

print("The status code is \(http200Status.statusCode)") // 杈撳嚭 "The status code is 200" print("The status message is \(http200Status.description)") // 杈撳嚭 "The status message is OK" 

浣滀负鍑芥暟杩斿洖鍊兼椂锛屽厓缁勯潪甯告湁鐢ㄣ�涓�釜鐢ㄦ潵鑾峰彇缃戦〉鐨勫嚱鏁板彲鑳戒細杩斿洖涓�釜(Int, String)鍏冪粍鏉ユ弿杩版槸鍚﹁幏鍙栨垚鍔熴�鍜屽彧鑳借繑鍥炰竴涓被鍨嬬殑鍊兼瘮杈冭捣鏉ワ紝涓�釜鍖呭惈涓や釜涓嶅悓绫诲瀷鍊肩殑鍏冪粍鍙互璁╁嚱鏁扮殑杩斿洖淇℃伅鏇存湁鐢ㄣ�璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/06_Functions.html#Function_Parameters_and_Return_Values">鍑芥暟鍙傛暟涓庤繑鍥炲�銆�/p>

娉ㄦ剰锛�br />鍏冪粍鍦ㄤ复鏃剁粍缁囧�鐨勬椂鍊欏緢鏈夌敤锛屼絾鏄苟涓嶉�鍚堝垱寤哄鏉傜殑鏁版嵁缁撴瀯銆傚鏋滀綘鐨勬暟鎹粨鏋勫苟涓嶆槸涓存椂浣跨敤锛岃浣跨敤绫绘垨鑰呯粨鏋勪綋鑰屼笉鏄厓缁勩�璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/09_Classes_and_Structures.html">绫诲拰缁撴瀯浣�/a>銆�/p>

鍙�绫诲瀷

浣跨敤鍙�绫诲瀷锛坥ptionals锛�/em>鏉ュ鐞嗗�鍙兘缂哄け鐨勬儏鍐点�鍙�绫诲瀷琛ㄧず锛�/p>

• 鏈夊�锛岀瓑浜�x

鎴栬�

• 娌℃湁鍊�/li>

娉ㄦ剰锛�br />C 鍜�Objective-C 涓苟娌℃湁鍙�绫诲瀷杩欎釜姒傚康銆傛渶鎺ヨ繎鐨勬槸 Objective-C 涓殑涓�釜鐗规�锛屼竴涓柟娉曡涓嶈繑鍥炰竴涓璞¤涓嶈繑鍥�code>nil锛�code>nil琛ㄧず“缂哄皯涓�釜鍚堟硶鐨勫璞�rdquo;銆傜劧鑰岋紝杩欏彧瀵瑰璞¤捣浣滅敤——瀵逛簬缁撴瀯浣擄紝鍩烘湰鐨�C 绫诲瀷鎴栬�鏋氫妇绫诲瀷涓嶈捣浣滅敤銆傚浜庤繖浜涚被鍨嬶紝Objective-C 鏂规硶涓�埇浼氳繑鍥炰竴涓壒娈婂�锛堟瘮濡�code>NSNotFound锛夋潵鏆楃ず鍊肩己澶便�杩欑鏂规硶鍋囪鏂规硶鐨勮皟鐢ㄨ�鐭ラ亾骞惰寰楀鐗规畩鍊艰繘琛屽垽鏂�鐒惰�锛孲wift 鐨勫彲閫夌被鍨嬪彲浠ヨ浣犳殫绀�em>浠绘剰绫诲瀷鐨勫�缂哄け锛屽苟涓嶉渶瑕佷竴涓壒娈婂�銆�/p>

鏉ョ湅涓�釜渚嬪瓙銆係wift 鐨�code>String绫诲瀷鏈変竴绉嶆瀯閫犲櫒锛屼綔鐢ㄦ槸灏嗕竴涓�code>String鍊艰浆鎹㈡垚涓�釜Int鍊笺�鐒惰�锛屽苟涓嶆槸鎵�湁鐨勫瓧绗︿覆閮藉彲浠ヨ浆鎹㈡垚涓�釜鏁存暟銆傚瓧绗︿覆"123"鍙互琚浆鎹㈡垚鏁板瓧123锛屼絾鏄瓧绗︿覆"hello, world"涓嶈銆�/p>

涓嬮潰鐨勪緥瀛愪娇鐢ㄨ繖绉嶆瀯閫犲櫒鏉ュ皾璇曞皢涓�釜String杞崲鎴�code>Int锛�/p>

let possibleNumber = "123" let convertedNumber = Int(possibleNumber) // convertedNumber 琚帹娴嬩负绫诲瀷 "Int?"锛�鎴栬�绫诲瀷 "optional Int" 

鍥犱负璇ユ瀯閫犲櫒鍙兘浼氬け璐ワ紝鎵�互瀹冭繑鍥炰竴涓�em>鍙�绫诲瀷锛坥ptional锛�code>Int锛岃�涓嶆槸涓�釜Int銆備竴涓彲閫夌殑Int琚啓浣�code>Int?鑰屼笉鏄�code>Int銆傞棶鍙锋殫绀哄寘鍚殑鍊兼槸鍙�绫诲瀷锛屼篃灏辨槸璇村彲鑳藉寘鍚�code>Int鍊间篃鍙兘涓嶅寘鍚�銆傦紙涓嶈兘鍖呭惈鍏朵粬浠讳綍鍊兼瘮濡�code>Bool鍊兼垨鑰�code>String鍊笺�鍙兘鏄�code>Int鎴栬�浠�箞閮芥病鏈夈�锛�/p>

nil

浣犲彲浠ョ粰鍙�鍙橀噺璧嬪�涓�code>nil鏉ヨ〃绀哄畠娌℃湁鍊硷細

var serverResponseCode: Int? = 404 // serverResponseCode 鍖呭惈涓�釜鍙�鐨�Int 鍊�404 serverResponseCode = nil // serverResponseCode 鐜板湪涓嶅寘鍚� 

娉ㄦ剰锛�br />nil涓嶈兘鐢ㄤ簬闈炲彲閫夌殑甯搁噺鍜屽彉閲忋�濡傛灉浣犵殑浠ｇ爜涓湁甯搁噺鎴栬�鍙橀噺闇�澶勭悊鍊肩己澶辩殑鎯呭喌锛岃鎶婂畠浠０鏄庢垚瀵瑰簲鐨勫彲閫夌被鍨嬨�

濡傛灉浣犲０鏄庝竴涓彲閫夊父閲忔垨鑰呭彉閲忎絾鏄病鏈夎祴鍊硷紝瀹冧滑浼氳嚜鍔ㄨ璁剧疆涓�code>nil锛�/p>

var surveyAnswer: String? // surveyAnswer 琚嚜鍔ㄨ缃负 nil 

娉ㄦ剰锛�br />Swift 鐨�code>nil鍜�Objective-C 涓殑nil骞朵笉涓�牱銆傚湪 Objective-C 涓紝nil鏄竴涓寚鍚戜笉瀛樺湪瀵硅薄鐨勬寚閽堛�鍦�Swift 涓紝nil涓嶆槸鎸囬拡——瀹冩槸涓�釜纭畾鐨勫�锛岀敤鏉ヨ〃绀哄�缂哄け銆備换浣曠被鍨嬬殑鍙�鐘舵�閮藉彲浠ヨ璁剧疆涓�code>nil锛屼笉鍙槸瀵硅薄绫诲瀷銆�/p>

if 璇彞浠ュ強寮哄埗瑙ｆ瀽

浣犲彲浠ヤ娇鐢�code>if璇彞鍜�code>nil姣旇緝鏉ュ垽鏂竴涓彲閫夊�鏄惁鍖呭惈鍊笺�浣犲彲浠ヤ娇鐢�ldquo;鐩哥瓑”(==)鎴�ldquo;涓嶇瓑”(!=)鏉ユ墽琛屾瘮杈冦�

濡傛灉鍙�绫诲瀷鏈夊�锛屽畠灏嗕笉绛変簬nil:

if convertedNumber != nil { print("convertedNumber contains some integer value.") } // 杈撳嚭 "convertedNumber contains some integer value." 

褰撲綘纭畾鍙�绫诲瀷纭疄鍖呭惈鍊间箣鍚庯紝浣犲彲浠ュ湪鍙�鐨勫悕瀛楀悗闈㈠姞涓�釜鎰熷徆鍙凤紙!锛夋潵鑾峰彇鍊笺�杩欎釜鎯婂徆鍙疯〃绀�ldquo;鎴戠煡閬撹繖涓彲閫夋湁鍊硷紝璇蜂娇鐢ㄥ畠銆�rdquo;杩欒绉颁负鍙�鍊肩殑寮哄埗瑙ｆ瀽锛坒orced unwrapping锛�/em>锛�/p>

if convertedNumber != nil { print("convertedNumber has an integer value of \(convertedNumber!).") } // 杈撳嚭 "convertedNumber has an integer value of 123." 

鏇村鍏充簬if璇彞鐨勫唴瀹癸紝璇峰弬鑰�a href="http://www.swift51.com/swift2.1/chapter2/05_Control_Flow.html">鎺у埗娴�/a>銆�/p>

娉ㄦ剰锛�br />浣跨敤!鏉ヨ幏鍙栦竴涓笉瀛樺湪鐨勫彲閫夊�浼氬鑷磋繍琛屾椂閿欒銆備娇鐢�code>!鏉ュ己鍒惰В鏋愬�涔嬪墠锛屼竴瀹氳纭畾鍙�鍖呭惈涓�釜闈�code>nil鐨勫�銆�/p>

鍙�缁戝畾

浣跨敤鍙�缁戝畾锛坥ptional binding锛�/em>鏉ュ垽鏂彲閫夌被鍨嬫槸鍚﹀寘鍚�锛屽鏋滃寘鍚氨鎶婂�璧嬬粰涓�釜涓存椂甯搁噺鎴栬�鍙橀噺銆傚彲閫夌粦瀹氬彲浠ョ敤鍦�code>if鍜�code>while璇彞涓紝杩欐潯璇彞涓嶄粎鍙互鐢ㄦ潵鍒ゆ柇鍙�绫诲瀷涓槸鍚︽湁鍊硷紝鍚屾椂鍙互灏嗗彲閫夌被鍨嬩腑鐨勫�璧嬬粰涓�釜甯搁噺鎴栬�鍙橀噺銆�code>if鍜�code>while璇彞锛岃鍙傝�鎺у埗娴�/a>銆�/p>

鍍忎笅闈㈣繖鏍峰湪if璇彞涓啓涓�釜鍙�缁戝畾锛�/p>

if let constantName = someOptional { statements } 

浣犲彲浠ュ儚涓婇潰杩欐牱浣跨敤鍙�缁戝畾鏉ラ噸鍐�code>possibleNumber杩欎釜渚嬪瓙锛�/p>

if let actualNumber = Int(possibleNumber) { print("\'\(possibleNumber)\' has an integer value of \(actualNumber)") } else { print("\'\(possibleNumber)\' could not be converted to an integer") } // 杈撳嚭 "'123' has an integer value of 123" 

杩欐浠ｇ爜鍙互琚悊瑙ｄ负锛�/p>

“濡傛灉Int(possibleNumber)杩斿洖鐨勫彲閫�code>Int鍖呭惈涓�釜鍊硷紝鍒涘缓涓�釜鍙仛actualNumber鐨勬柊甯搁噺骞跺皢鍙�鍖呭惈鐨勫�璧嬬粰瀹冦�”

濡傛灉杞崲鎴愬姛锛�code>actualNumber甯搁噺鍙互鍦�code>if璇彞鐨勭涓�釜鍒嗘敮涓娇鐢ㄣ�瀹冨凡缁忚鍙�绫诲瀷 鍖呭惈鐨�/em> 鍊煎垵濮嬪寲杩囷紝鎵�互涓嶉渶瑕佸啀浣跨敤!鍚庣紑鏉ヨ幏鍙栧畠鐨勫�銆傚湪杩欎釜渚嬪瓙涓紝actualNumber鍙鐢ㄦ潵杈撳嚭杞崲缁撴灉銆�/p>

浣犲彲浠ュ湪鍙�缁戝畾涓娇鐢ㄥ父閲忓拰鍙橀噺銆傚鏋滀綘鎯冲湪if璇彞鐨勭涓�釜鍒嗘敮涓搷浣�code>actualNumber鐨勫�锛屼綘鍙互鏀规垚if var actualNumber锛岃繖鏍峰彲閫夌被鍨嬪寘鍚殑鍊煎氨浼氳璧嬬粰涓�釜鍙橀噺鑰岄潪甯搁噺銆�/p>

浣犲彲浠ュ寘鍚涓彲閫夌粦瀹氬湪if璇彞涓紝骞朵娇鐢�code>where瀛愬彞鍋氬竷灏斿�鍒ゆ柇銆�/p>

if let firstNumber = Int("4"), secondNumber = Int("42") where firstNumber < secondNumber { print("\(firstNumber) < \(secondNumber)") } // prints "4 < 42" 

闅愬紡瑙ｆ瀽鍙�绫诲瀷

濡備笂鎵�堪锛屽彲閫夌被鍨嬫殫绀轰簡甯搁噺鎴栬�鍙橀噺鍙互“娌℃湁鍊�rdquo;銆傚彲閫夊彲浠ラ�杩�code>if璇彞鏉ュ垽鏂槸鍚︽湁鍊硷紝濡傛灉鏈夊�鐨勮瘽鍙互閫氳繃鍙�缁戝畾鏉ヨВ鏋愬�銆�/p>

鏈夋椂鍊欏湪绋嬪簭鏋舵瀯涓紝绗竴娆¤璧嬪�涔嬪悗锛屽彲浠ョ‘瀹氫竴涓彲閫夌被鍨�em>鎬讳細鏈夊�銆傚湪杩欑鎯呭喌涓嬶紝姣忔閮借鍒ゆ柇鍜岃В鏋愬彲閫夊�鏄潪甯镐綆鏁堢殑锛屽洜涓哄彲浠ョ‘瀹氬畠鎬讳細鏈夊�銆�/p>

杩欑绫诲瀷鐨勫彲閫夌姸鎬佽瀹氫箟涓洪殣寮忚В鏋愬彲閫夌被鍨嬶紙implicitly unwrapped optionals锛夈�鎶婃兂瑕佺敤浣滃彲閫夌殑绫诲瀷鐨勫悗闈㈢殑闂彿锛�code>String?锛夋敼鎴愭劅鍙瑰彿锛�code>String!锛夋潵澹版槑涓�釜闅愬紡瑙ｆ瀽鍙�绫诲瀷銆�/p>

褰撳彲閫夌被鍨嬭绗竴娆¤祴鍊间箣鍚庡氨鍙互纭畾涔嬪悗涓�洿鏈夊�鐨勬椂鍊欙紝闅愬紡瑙ｆ瀽鍙�绫诲瀷闈炲父鏈夌敤銆傞殣寮忚В鏋愬彲閫夌被鍨嬩富瑕佽鐢ㄥ湪 Swift 涓被鐨勬瀯閫犺繃绋嬩腑锛岃鍙傝�鏃犱富寮曠敤浠ュ強闅愬紡瑙ｆ瀽鍙�灞炴�銆�/p>

涓�釜闅愬紡瑙ｆ瀽鍙�绫诲瀷鍏跺疄灏辨槸涓�釜鏅�鐨勫彲閫夌被鍨嬶紝浣嗘槸鍙互琚綋鍋氶潪鍙�绫诲瀷鏉ヤ娇鐢紝骞朵笉闇�姣忔閮戒娇鐢ㄨВ鏋愭潵鑾峰彇鍙�鍊笺�涓嬮潰鐨勪緥瀛愬睍绀轰簡鍙�绫诲瀷String鍜岄殣寮忚В鏋愬彲閫夌被鍨�code>String涔嬮棿鐨勫尯鍒細

let possibleString: String? = "An optional string." let forcedString: String = possibleString! // 闇�鎯婂徆鍙锋潵鑾峰彇鍊� let assumedString: String! = "An implicitly unwrapped optional string." let implicitString: String = assumedString // 涓嶉渶瑕佹劅鍙瑰彿 

浣犲彲浠ユ妸闅愬紡瑙ｆ瀽鍙�绫诲瀷褰撳仛涓�釜鍙互鑷姩瑙ｆ瀽鐨勫彲閫夌被鍨嬨�浣犺鍋氱殑鍙槸澹版槑鐨勬椂鍊欐妸鎰熷徆鍙锋斁鍒扮被鍨嬬殑缁撳熬锛岃�涓嶆槸姣忔鍙栧�鐨勫彲閫夊悕瀛楃殑缁撳熬銆�/p>

娉ㄦ剰锛�br />濡傛灉浣犲湪闅愬紡瑙ｆ瀽鍙�绫诲瀷娌℃湁鍊肩殑鏃跺�灏濊瘯鍙栧�锛屼細瑙﹀彂杩愯鏃堕敊璇�鍜屼綘鍦ㄦ病鏈夊�鐨勬櫘閫氬彲閫夌被鍨嬪悗闈㈠姞涓�釜鎯婂徆鍙蜂竴鏍枫�

浣犱粛鐒跺彲浠ユ妸闅愬紡瑙ｆ瀽鍙�绫诲瀷褰撳仛鏅�鍙�绫诲瀷鏉ュ垽鏂畠鏄惁鍖呭惈鍊硷細

if assumedString != nil { print(assumedString) } // 杈撳嚭 "An implicitly unwrapped optional string." 

浣犱篃鍙互鍦ㄥ彲閫夌粦瀹氫腑浣跨敤闅愬紡瑙ｆ瀽鍙�绫诲瀷鏉ユ鏌ュ苟瑙ｆ瀽瀹冪殑鍊硷細

if let definiteString = assumedString { print(definiteString) } // 杈撳嚭 "An implicitly unwrapped optional string." 

娉ㄦ剰锛�br />濡傛灉涓�釜鍙橀噺涔嬪悗鍙兘鍙樻垚nil鐨勮瘽璇蜂笉瑕佷娇鐢ㄩ殣寮忚В鏋愬彲閫夌被鍨嬨�濡傛灉浣犻渶瑕佸湪鍙橀噺鐨勭敓鍛藉懆鏈熶腑鍒ゆ柇鏄惁鏄�code>nil鐨勮瘽锛岃浣跨敤鏅�鍙�绫诲瀷銆�/p>

閿欒澶勭悊

浣犲彲浠ヤ娇鐢�em>閿欒澶勭悊锛坋rror handling锛�/em>鏉ュ簲瀵圭▼搴忔墽琛屼腑鍙兘浼氶亣鍒扮殑閿欒鏉′欢銆�/p>

鐩稿浜庡彲閫変腑杩愮敤鍊肩殑瀛樺湪涓庣己澶辨潵琛ㄨ揪鍑芥暟鐨勬垚鍔熶笌澶辫触锛岄敊璇鐞嗗彲浠ユ帹鏂け璐ョ殑鍘熷洜锛屽苟浼犳挱鑷崇▼搴忕殑鍏朵粬閮ㄥ垎銆�/p>

褰撲竴涓嚱鏁伴亣鍒伴敊璇潯浠讹紝瀹冭兘鎶ラ敊銆傝皟鐢ㄥ嚱鏁扮殑鍦版柟鑳芥姏鍑洪敊璇秷鎭苟鍚堢悊澶勭悊銆�/p>

func canThrowAnError() throws { // 杩欎釜鍑芥暟鏈夊彲鑳芥姏鍑洪敊璇� } 

涓�釜鍑芥暟鍙互閫氳繃鍦ㄥ０鏄庝腑娣诲姞throws鍏抽敭璇嶆潵鎶涘嚭閿欒娑堟伅銆傚綋浣犵殑鍑芥暟鑳芥姏鍑洪敊璇秷鎭椂, 浣犲簲璇ュ湪琛ㄨ揪寮忎腑鍓嶇疆try鍏抽敭璇嶃�

do { try canThrowAnError() // 娌℃湁閿欒娑堟伅鎶涘嚭 } catch { // 鏈変竴涓敊璇秷鎭姏鍑� } 

涓�釜do璇彞鍒涘缓浜嗕竴涓柊鐨勫寘鍚綔鐢ㄥ煙,浣垮緱閿欒鑳借浼犳挱鍒颁竴涓垨澶氫釜catch浠庡彞銆�/p>

杩欓噷鏈変竴涓敊璇鐞嗗浣曠敤鏉ュ簲瀵逛笉鍚岄敊璇潯浠剁殑渚嬪瓙銆�/p>

func makeASandwich() throws { // ... } do { try makeASandwich() eatASandwich() } catch Error.OutOfCleanDishes { washDishes() } catch Error.MissingIngredients(let ingredients) { buyGroceries(ingredients) } 

鍦ㄦ渚嬩腑锛�code>makeASandwich()锛堝仛涓�釜涓夋槑娌伙級鍑芥暟浼氭姏鍑轰竴涓敊璇秷鎭鏋滄病鏈夊共鍑�殑鐩樺瓙鎴栬�鏌愪釜鍘熸枡缂哄け銆傚洜涓�code>makeASandwich()鎶涘嚭閿欒锛屽嚱鏁拌皟鐢ㄨ鍖呰９鍦�code>try琛ㄨ揪寮忎腑銆傚皢鍑芥暟鍖呰９鍦ㄤ竴涓�code>do璇彞涓�浠讳綍琚姏鍑虹殑閿欒浼氳浼犳挱鍒版彁渚涚殑catch浠庡彞涓�

濡傛灉娌℃湁閿欒琚姏鍑� eatASandwich()鍑芥暟浼氳璋冪敤銆傚鏋滀竴涓尮閰�code>Error.OutOfCleanDishes鐨勯敊璇鎶涘嚭,washDishes鍑芥暟浼氳璋冪敤銆傚鏋滀竴涓尮閰�code>Error.MissingIngredients鐨勯敊璇鎶涘嚭锛�code>buyGroceries(_:)鍑芥暟浼氶殢鐫�catch鎵�崟鎹夊埌鐨勫叧鑱斿�[String]琚皟鐢ㄣ�

鎶涘嚭锛屾崟鎹夛紝浠ュ強浼犳挱閿欒浼氬湪閿欒澶勭悊绔犺妭璇︾粏璇存槑銆�/p>

鏂█

鍙�绫诲瀷鍙互璁╀綘鍒ゆ柇鍊兼槸鍚﹀瓨鍦紝浣犲彲浠ュ湪浠ｇ爜涓紭闆呭湴澶勭悊鍊肩己澶辩殑鎯呭喌銆傜劧鑰岋紝鍦ㄦ煇浜涙儏鍐典笅锛屽鏋滃�缂哄け鎴栬�鍊煎苟涓嶆弧瓒崇壒瀹氱殑鏉′欢锛屼綘鐨勪唬鐮佸彲鑳芥病鍔炴硶缁х画鎵ц銆傝繖鏃讹紝浣犲彲浠ュ湪浣犵殑浠ｇ爜涓Е鍙戜竴涓�em>鏂█锛坅ssertion锛�/em>鏉ョ粨鏉熶唬鐮佽繍琛屽苟閫氳繃璋冭瘯鏉ユ壘鍒板�缂哄け鐨勫師鍥犮�

浣跨敤鏂█杩涜璋冭瘯

鏂█浼氬湪杩愯鏃跺垽鏂竴涓�杈戞潯浠舵槸鍚︿负true銆備粠瀛楅潰鎰忔�鏉ヨ锛屾柇瑷�ldquo;鏂█”涓�釜鏉′欢鏄惁涓虹湡銆備綘鍙互浣跨敤鏂█鏉ヤ繚璇佸湪杩愯鍏朵粬浠ｇ爜涔嬪墠锛屾煇浜涢噸瑕佺殑鏉′欢宸茬粡琚弧瓒炽�濡傛灉鏉′欢鍒ゆ柇涓�code>true锛屼唬鐮佽繍琛屼細缁х画杩涜锛涘鏋滄潯浠跺垽鏂负false锛屼唬鐮佹墽琛岀粨鏉燂紝浣犵殑搴旂敤琚粓姝€�

濡傛灉浣犵殑浠ｇ爜鍦ㄨ皟璇曠幆澧冧笅瑙﹀彂浜嗕竴涓柇瑷�紝姣斿浣犲湪 Xcode 涓瀯寤哄苟杩愯涓�釜搴旂敤锛屼綘鍙互娓呮鍦扮湅鍒颁笉鍚堟硶鐨勭姸鎬佸彂鐢熷湪鍝噷骞舵鏌ユ柇瑷�瑙﹀彂鏃朵綘鐨勫簲鐢ㄧ殑鐘舵�銆傛澶栵紝鏂█鍏佽浣犻檮鍔犱竴鏉¤皟璇曚俊鎭�

浣犲彲浠ヤ娇鐢ㄥ叏灞�code>assert(_:_file:line:)鍑芥暟鏉ュ啓涓�釜鏂█銆傚悜杩欎釜鍑芥暟浼犲叆涓�釜缁撴灉涓�code>true鎴栬�false鐨勮〃杈惧紡浠ュ強涓�潯淇℃伅锛屽綋琛ㄨ揪寮忕殑缁撴灉涓�code>false鐨勬椂鍊欒繖鏉′俊鎭細琚樉绀猴細

let age = -3 assert(age >= 0, "A person's age cannot be less than zero") // 鍥犱负 age < 0锛屾墍浠ユ柇瑷�細瑙﹀彂 

鍦ㄨ繖涓緥瀛愪腑锛屽彧鏈�code>age >= 0涓�code>true鐨勬椂鍊欙紝鍗�code>age鐨勫�闈炶礋鐨勬椂鍊欙紝浠ｇ爜鎵嶄細缁х画鎵ц銆傚鏋�code>age鐨勫�鏄礋鏁帮紝灏卞儚浠ｇ爜涓偅鏍凤紝age >= 0涓�code>false锛屾柇瑷�瑙﹀彂锛岀粓姝㈠簲鐢ㄣ�

濡傛灉涓嶉渶瑕佹柇瑷�俊鎭紝鍙互鐪佺暐锛屽氨鍍忚繖鏍凤細

assert(age >= 0) 

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