{"id":4089,"date":"2025-06-04T11:35:34","date_gmt":"2025-06-05T04:08:34","guid":{"rendered":"https:\/\/badgameshow.com\/steven\/?p=4089"},"modified":"2025-06-05T11:35:34","modified_gmt":"2025-06-05T04:08:34","slug":"%e4%ba%86%e8%a7%a3swift%e4%b8%ad%e4%b8%8d%e8%83%bd%e5%b0%8dget-only%e5%b1%ac%e6%80%a7%e9%80%b2%e8%a1%8c%e8%b3%a6%e5%80%bc%e7%9a%84%e5%8e%9f%e5%9b%a0","status":"publish","type":"post","link":"https:\/\/badgameshow.com\/steven\/swift\/%e4%ba%86%e8%a7%a3swift%e4%b8%ad%e4%b8%8d%e8%83%bd%e5%b0%8dget-only%e5%b1%ac%e6%80%a7%e9%80%b2%e8%a1%8c%e8%b3%a6%e5%80%bc%e7%9a%84%e5%8e%9f%e5%9b%a0\/","title":{"rendered":"\u6df1\u5165\u4e86\u89e3 Swift \u7684 Get-Only \u5c6c\u6027\uff1a\u907f\u514d\u300cCannot assign to value\u300d\u932f\u8aa4\u7684\u6700\u4f73\u5be6\u8e10"},"content":{"rendered":"<p><meta name=\"keywords\" content=\"Swift, Get-only Property, Cannot assign to value, Swift Programming, Swift Error Handling\"><\/p>\n<h1>\u6df1\u5165\u4e86\u89e3 Swift \u7684 Get-Only \u5c6c\u6027\uff1a\u907f\u514d\u300cCannot assign to value\u300d\u932f\u8aa4\u7684\u6700\u4f73\u5be6\u8e10<\/h1>\n<p>Swift \u662f\u4e00\u7a2e\u5f37\u5927\u7684\u7a0b\u5f0f\u8a9e\u8a00\uff0c\u5177\u5099\u975c\u614b\u985e\u578b\u6aa2\u67e5\u548c\u5b89\u5168\u6027\u3002\u7136\u800c\uff0c\u5728\u4f7f\u7528 Swift \u6642\uff0c\u4f60\u53ef\u80fd\u6703\u9047\u5230\u4e00\u4e9b\u932f\u8aa4\u8a0a\u606f\uff0c\u4f8b\u5982\u300cCannot assign to value: &#8216;X&#8217; is a get-only property\u300d\u3002\u9019\u7bc7\u6587\u7ae0\u5c07\u6df1\u5165\u89e3\u6790\u9019\u500b\u932f\u8aa4\u7684\u539f\u56e0\uff0c\u4e26\u63d0\u4f9b\u5be6\u7528\u7684\u89e3\u6c7a\u65b9\u6848\u53ca\u6700\u4f73\u5be6\u8e10\u3002<\/p>\n<h2>\u4ec0\u9ebc\u662f Get-Only \u5c6c\u6027\uff1f<\/h2>\n<p>\u5728 Swift \u4e2d\uff0c\u5c6c\u6027\u53ef\u4ee5\u88ab\u5b9a\u7fa9\u70ba\u53ea\u80fd\u8b80\u53d6\u7684\uff08Get-Only\uff09\uff0c\u9019\u610f\u5473\u8457\u9019\u4e9b\u5c6c\u6027\u53ea\u80fd\u88ab\u8a2a\u554f\uff0c\u800c\u4e0d\u80fd\u88ab\u4fee\u6539\u3002\u9019\u901a\u5e38\u662f\u901a\u904e\u4f7f\u7528 `let` \u95dc\u9375\u5b57\u4f86\u5b9a\u7fa9\u7684\u3002<\/p>\n<h2>\u70ba\u4ec0\u9ebc\u6703\u51fa\u73fe\u300cCannot assign to value\u300d\u932f\u8aa4\uff1f<\/h2>\n<p>\u7576\u4f60\u5617\u8a66\u5c0d\u4e00\u500b Get-Only \u5c6c\u6027\u8ce6\u503c\u6642\uff0cSwift \u6703\u7522\u751f\u932f\u8aa4\u6d88\u606f\u3002\u9019\u662f\u7531\u65bc\u5c6c\u6027\u88ab\u8a2d\u8a08\u70ba\u53ea\u8b80\uff0c\u7121\u6cd5\u6539\u8b8a\u5176\u503c\u3002\u4ee5\u4e0b\u662f\u932f\u8aa4\u7684\u793a\u4f8b\uff1a<\/p>\n<pre class=\"brush: swift\">\nclass Person {\n    let name: String\n    \n    init(name: String) {\n        self.name = name\n    }\n}\n\nlet person = Person(name: \"John\")\n\n\/\/ \u9019\u884c\u4ee3\u78bc\u5c07\u6703\u7522\u751f\u932f\u8aa4\nperson.name = \"Jane\" \/\/ Error: Cannot assign to value: 'name' is a get-only property\n<\/pre>\n<h2>\u5982\u4f55\u907f\u514d\u9019\u500b\u932f\u8aa4\uff1f<\/h2>\n<p>\u82e5\u4f60\u9700\u8981\u5c0d\u5c6c\u6027\u9032\u884c\u4fee\u6539\uff0c\u61c9\u8003\u616e\u4f7f\u7528 `var` \u95dc\u9375\u5b57\u4f86\u5b9a\u7fa9\u53ef\u8b8a\u5c6c\u6027\u3002\u9019\u6a23\uff0c\u4f60\u5c31\u53ef\u4ee5\u96a8\u6642\u5c0d\u5176\u9032\u884c\u8ce6\u503c\uff1a<\/p>\n<pre class=\"brush: swift\">\nclass MutablePerson {\n    var name: String\n    \n    init(name: String) {\n        self.name = name\n    }\n}\n\nlet mutablePerson = MutablePerson(name: \"John\")\nmutablePerson.name = \"Jane\" \/\/ \u9019\u884c\u4ee3\u78bc\u5c07\u6b63\u5e38\u5de5\u4f5c\n<\/pre>\n<h2>\u5be6\u4f5c\u7bc4\u4f8b\uff1a\u4f7f\u7528 Get-Only \u548c\u53ef\u8b8a\u5c6c\u6027<\/h2>\n<p>\u4ee5\u4e0b\u662f\u4e00\u500b\u5b8c\u6574\u7684\u7bc4\u4f8b\uff0c\u5c55\u793a\u4e86\u5982\u4f55\u9748\u6d3b\u904b\u7528 Get-Only \u548c\u53ef\u8b8a\u5c6c\u6027\uff1a<\/p>\n<pre class=\"brush: swift\">\nclass Employee {\n    private var _salary: Double\n    \n    var salary: Double {\n        return _salary\n    }\n    \n    init(salary: Double) {\n        self._salary = salary\n    }\n    \n    func updateSalary(newSalary: Double) {\n        _salary = newSalary\n    }\n}\n\nlet employee = Employee(salary: 50000)\nprint(\"\u539f\u59cb\u85aa\u6c34\uff1a\\(employee.salary)\")\n\n\/\/ \u66f4\u65b0\u85aa\u6c34\nemployee.updateSalary(newSalary: 60000)\nprint(\"\u66f4\u65b0\u5f8c\u85aa\u6c34\uff1a\\(employee.salary)\")\n<\/pre>\n<h2>\u932f\u8aa4\u6392\u9664\u5efa\u8b70<\/h2>\n<ul>\n<li>\u5728\u5b9a\u7fa9\u5c6c\u6027\u6642\uff0c\u6aa2\u67e5\u662f\u5426\u9700\u8981\u8b8a\u66f4\u5c6c\u6027\u70ba\u53ef\u8b8a\u7684\u3002<\/li>\n<li>\u4f7f\u7528\u5408\u9069\u7684\u5b58\u53d6\u4fee\u98fe\u8a5e\uff08\u5982 `private`\uff09\u4f86\u4fdd\u8b77\u5c6c\u6027\uff0c\u4f7f\u5176\u4e0d\u88ab\u5916\u90e8\u76f4\u63a5\u4fee\u6539\u3002<\/li>\n<li>\u82e5\u5fc5\u9808\u4f7f\u7528 Get-Only \u5c6c\u6027\uff0c\u8003\u616e\u6dfb\u52a0\u65b9\u6cd5\u4f86\u63d0\u4f9b\u66f4\u65b0\u6a5f\u5236\u3002<\/li>\n<\/ul>\n<h2>\u5ef6\u4f38\u61c9\u7528<\/h2>\n<p>\u4e86\u89e3 Get-Only \u5c6c\u6027\u5728 Swift \u4e2d\u7684\u904b\u4f5c\u65b9\u5f0f\u5c0d\u65bc\u7de8\u5beb\u5b89\u5168\u4e14\u53ef\u7dad\u8b77\u7684\u7a0b\u5f0f\u78bc\u662f\u81f3\u95dc\u91cd\u8981\u7684\u3002\u900f\u904e\u638c\u63e1\u9019\u4e9b\u6982\u5ff5\uff0c\u4f60\u5c07\u80fd\u5920\u66f4\u6709\u6548\u5730\u8655\u7406 Swift \u4e2d\u7684\u5c6c\u6027\u548c\u932f\u8aa4\u3002<\/p>\n<h2>\u7d50\u8ad6<\/h2>\n<p>\u7e3d\u800c\u8a00\u4e4b\uff0c\u300cCannot assign to value: &#8216;X&#8217; is a get-only property\u300d\u662f Swift \u4e2d\u4e00\u500b\u5e38\u898b\u7684\u932f\u8aa4\u8a0a\u606f\uff0c\u8868\u793a\u4f60\u5617\u8a66\u5c0d\u4e00\u500b\u53ea\u80fd\u8b80\u53d6\u7684\u5c6c\u6027\u8ce6\u503c\u3002\u5982\u679c\u4f60\u60f3\u8981\u5c0d\u5c6c\u6027\u8ce6\u503c\uff0c\u5fc5\u9808\u5c07\u5176\u5b9a\u7fa9\u70ba `var`\uff0c\u6216\u900f\u904e\u65b9\u6cd5\u9032\u884c\u66f4\u65b0\u3002<\/p>\n<h2>Q&#038;A\uff08\u5e38\u898b\u554f\u984c\u89e3\u7b54\uff09<\/h2>\n<h3>Q1: \u5982\u4f55\u77e5\u9053\u4e00\u500b\u5c6c\u6027\u662f Get-Only\uff1f<\/h3>\n<p>A1: \u901a\u5e38\uff0c\u82e5\u5c6c\u6027\u4f7f\u7528 `let` \u95dc\u9375\u5b57\u5b9a\u7fa9\u4e14\u6c92\u6709\u63d0\u4f9b setter\uff0c\u5247\u5b83\u662f Get-Only \u5c6c\u6027\u3002<\/p>\n<h3>Q2: \u6211\u53ef\u4ee5\u5c07 Get-Only \u5c6c\u6027\u8f49\u63db\u70ba\u53ef\u8b8a\u5c6c\u6027\u55ce\uff1f<\/h3>\n<p>A2: \u662f\u7684\uff0c\u4f60\u53ef\u4ee5\u901a\u904e\u5c07\u5c6c\u6027\u5b9a\u7fa9\u70ba `var` \u4f86\u4f7f\u5176\u53ef\u8b8a\uff0c\u4f46\u9019\u5c07\u6539\u8b8a\u5176\u539f\u672c\u7684\u8a2d\u8a08\u76ee\u7684\u3002<\/p>\n<h3>Q3: \u5982\u4f55\u5b89\u5168\u5730\u66f4\u65b0 Get-Only \u5c6c\u6027\uff1f<\/h3>\n<p>A3: \u4f60\u53ef\u4ee5\u4f7f\u7528\u65b9\u6cd5\u4f86\u63d0\u4f9b\u66f4\u65b0\u6a5f\u5236\uff0c\u9019\u6a23\u53ef\u4ee5\u5728\u5167\u90e8\u63a7\u5236\u5c6c\u6027\u7684\u8b8a\u66f4\u908f\u8f2f\u3002<\/p>\n<p>&#8212;<\/p>\n<p>\u9019\u6a23\u7684\u5167\u5bb9\u512a\u5316\u4e0d\u50c5\u589e\u5f37\u4e86\u6587\u7ae0\u7684\u53ef\u8b80\u6027\uff0c\u9084\u63d0\u9ad8\u4e86\u5176\u5728\u641c\u5c0b\u5f15\u64ce\u4e0a\u7684\u6392\u540d\u548c\u53ef\u767c\u73fe\u6027\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6587\u7ae0\u6458\u8981\uff1a\u672c\u6587\u5c07\u89e3\u91cbSwift\u4e2d\u4e0d\u80fd\u5c0dGet-Only\u5c6c\u6027\u9032\u884c\u8ce6\u503c\u7684\u539f\u56e0\uff0c\u4e26\u63d0\u4f9b\u4e00\u4e9b\u89e3\u6c7a\u65b9\u6848\uff0c\u8b93\u958b\u767c\u8005\u80fd\u5920\u6b63\u78ba\u4f7f\u7528Get-Only\u5c6c\u6027\u3002<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[174,5],"tags":[173,9],"class_list":["post-4089","post","type-post","status-publish","format-standard","hentry","category-ios","category-swift","tag-ios","tag-swift"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack-related-posts":[],"jetpack_shortlink":"https:\/\/wp.me\/pcFK27-13X","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/posts\/4089","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/comments?post=4089"}],"version-history":[{"count":1,"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/posts\/4089\/revisions"}],"predecessor-version":[{"id":4090,"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/posts\/4089\/revisions\/4090"}],"wp:attachment":[{"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/media?parent=4089"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/categories?post=4089"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/badgameshow.com\/steven\/wp-json\/wp\/v2\/tags?post=4089"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}