{"id":30588,"date":"2023-05-19T09:05:35","date_gmt":"2023-05-19T01:05:35","guid":{"rendered":"https:\/\/docs.pingcode.com\/?p=30588"},"modified":"2023-07-31T00:01:12","modified_gmt":"2023-07-30T16:01:12","slug":"kvo%e7%9a%84%e6%9c%ac%e8%b4%a8%e6%98%af%e4%bb%80%e4%b9%88","status":"publish","type":"post","link":"https:\/\/docs.pingcode.com\/ask\/30588.html","title":{"rendered":"KVO\u7684\u672c\u8d28\u662f\u4ec0\u4e48"},"content":{"rendered":"<blockquote class=\"wp-block-quote\">\n<p>KVO\u662f\u6307\u5728\u8f6f\u4ef6\u5f00\u53d1\u4e2d\u4e00\u79cd\u89c2\u5bdf\u8005\u6a21\u5f0f\u7684\u5b9e\u73b0\uff0c\u5b83\u5141\u8bb8\u5bf9\u8c61\u76d1\u542c\u5176\u4ed6\u5bf9\u8c61\u7279\u5b9a\u5c5e\u6027\u7684\u53d8\u5316\uff0c\u5e76\u5728\u5c5e\u6027\u503c\u53d1\u751f\u6539\u53d8\u65f6\u5f97\u5230\u901a\u77e5\u3002KVO\u7684\u672c\u8d28\u662f\u901a\u8fc7\u8fd0\u884c\u65f6\u673a\u5236\u52a8\u6001\u751f\u6210\u5b50\u7c7b\uff0c\u5e76\u5728\u5b50\u7c7b\u4e2d\u91cd\u5199\u88ab\u89c2\u5bdf\u5c5e\u6027\u7684setter\u65b9\u6cd5\uff0c\u4ece\u800c\u5b9e\u73b0\u5c5e\u6027\u53d8\u5316\u7684\u76d1\u542c\u548c\u901a\u77e5\u3002<\/p>\n<\/blockquote>\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img fetchpriority=\"high\" alt=\"\" class=\"wp-image-30589\" decoding=\"async\" height=\"421\" sizes=\"(max-width: 680px) 100vw, 680px\" src=\"https:\/\/cdn-docs.pingcode.com\/wp-content\/uploads\/2023\/05\/\u95ee\u7b54\u6a21\u677f680-\u00d7-421-\u50cf\u7d20-2023-05-19T090433.083.jpg?x-oss-process=image\/auto-orient,1\/format,webp\" srcset=\"https:\/\/cdn-docs.pingcode.com\/wp-content\/uploads\/2023\/05\/\u95ee\u7b54\u6a21\u677f680-\u00d7-421-\u50cf\u7d20-2023-05-19T090433.083.jpg?x-oss-process=image\/auto-orient,1\/format,webp 680w, https:\/\/cdn-docs.pingcode.com\/wp-content\/uploads\/2023\/05\/\u95ee\u7b54\u6a21\u677f680-\u00d7-421-\u50cf\u7d20-2023-05-19T090433.083-300x186.jpg 300w\" width=\"680\"\/><\/figure>\n<\/div>\n<h2 class=\"wp-block-heading\">\u4e00\u3001KVO\u7684\u672c\u8d28<\/h2>\n<p>KVO\uff08Key-Value Observing\uff09\u662f\u6307\u5728\u8f6f\u4ef6\u5f00\u53d1\u4e2d\u4e00\u79cd\u89c2\u5bdf\u8005\u6a21\u5f0f\u7684\u5b9e\u73b0\uff0c\u5b83\u5141\u8bb8\u5bf9\u8c61\u76d1\u542c\u5176\u4ed6\u5bf9\u8c61\u7279\u5b9a\u5c5e\u6027\u7684\u53d8\u5316\uff0c\u5e76\u5728\u5c5e\u6027\u503c\u53d1\u751f\u6539\u53d8\u65f6\u5f97\u5230\u901a\u77e5\u3002KVO\u7684\u672c\u8d28\u662f\u901a\u8fc7\u8fd0\u884c\u65f6\u673a\u5236\u52a8\u6001\u751f\u6210\u5b50\u7c7b\uff0c\u5e76\u5728\u5b50\u7c7b\u4e2d\u91cd\u5199\u88ab\u89c2\u5bdf\u5c5e\u6027\u7684setter\u65b9\u6cd5\uff0c\u4ece\u800c\u5b9e\u73b0\u5c5e\u6027\u53d8\u5316\u7684\u76d1\u542c\u548c\u901a\u77e5\u3002<\/p>\n<p>\u5728KVO\u7684\u6a21\u5f0f\u4e2d\uff0c\u6709\u4e24\u4e2a\u4e3b\u8981\u7684\u89d2\u8272\uff1a\u88ab\u89c2\u5bdf\u5bf9\u8c61\uff08Observable\uff09\u548c\u89c2\u5bdf\u8005\uff08Observer\uff09\u3002\u88ab\u89c2\u5bdf\u5bf9\u8c61\u662f\u62e5\u6709\u67d0\u4e2a\u5c5e\u6027\u7684\u5bf9\u8c61\uff0c\u800c\u89c2\u5bdf\u8005\u662f\u5bf9\u8be5\u5c5e\u6027\u53d8\u5316\u611f\u5174\u8da3\u7684\u5bf9\u8c61\u3002<\/p>\n<p>KVO\u7684\u5b9e\u73b0\u539f\u7406\u5982\u4e0b\uff1a<\/p>\n<ul>\n<li>\u6ce8\u518c\u89c2\u5bdf\u8005\uff1a\u89c2\u5bdf\u8005\u901a\u8fc7\u8c03\u7528\u88ab\u89c2\u5bdf\u5bf9\u8c61\u7684<code>addObserver:forKeyPath:options:context:<\/code>\u65b9\u6cd5\uff0c\u5411\u88ab\u89c2\u5bdf\u5bf9\u8c61\u6ce8\u518c\u81ea\u5df1\u4f5c\u4e3a\u89c2\u5bdf\u8005\uff0c\u5e76\u6307\u5b9a\u8981\u89c2\u5bdf\u7684\u5c5e\u6027\u540d\u79f0\u3001\u89c2\u5bdf\u9009\u9879\u548c\u4e0a\u4e0b\u6587\u3002<\/li>\n<li>\u52a8\u6001\u751f\u6210\u5b50\u7c7b\uff1a\u88ab\u89c2\u5bdf\u5bf9\u8c61\u5728\u63a5\u6536\u5230\u89c2\u5bdf\u8005\u7684\u6ce8\u518c\u8bf7\u6c42\u540e\uff0c\u4f1a\u52a8\u6001\u751f\u6210\u4e00\u4e2a\u5b50\u7c7b\uff08\u901a\u5e38\u91c7\u7528\u8fd0\u884c\u65f6\u673a\u5236\uff09\uff0c\u8be5\u5b50\u7c7b\u7ee7\u627f\u81ea\u88ab\u89c2\u5bdf\u5bf9\u8c61\u7684\u539f\u59cb\u7c7b\u3002<\/li>\n<li>\u91cd\u5199setter\u65b9\u6cd5\uff1a\u751f\u6210\u7684\u5b50\u7c7b\u4f1a\u91cd\u5199\u88ab\u89c2\u5bdf\u5c5e\u6027\u7684setter\u65b9\u6cd5\u3002\u5728\u8fd9\u4e2asetter\u65b9\u6cd5\u4e2d\uff0c\u5b50\u7c7b\u4f1a\u5728\u8c03\u7528\u7236\u7c7b\u7684setter\u65b9\u6cd5\u4e4b\u524d\u548c\u4e4b\u540e\uff0c\u63d2\u5165\u5bf9\u89c2\u5bdf\u8005\u7684\u901a\u77e5\u4ee3\u7801\u3002<\/li>\n<li>\u5c5e\u6027\u53d8\u5316\u901a\u77e5\uff1a\u5f53\u88ab\u89c2\u5bdf\u5c5e\u6027\u7684setter\u65b9\u6cd5\u88ab\u8c03\u7528\u65f6\uff0c\u5b50\u7c7b\u4f1a\u68c0\u6d4b\u5230\u5c5e\u6027\u7684\u53d8\u5316\uff0c\u5e76\u89e6\u53d1\u901a\u77e5\u673a\u5236\u3002\u901a\u77e5\u673a\u5236\u4f1a\u8c03\u7528\u88ab\u89c2\u5bdf\u5bf9\u8c61\u7684<code>willChangeValueForKey:<\/code>\u548c<code>didChangeValueForKey:<\/code>\u65b9\u6cd5\uff0c\u5206\u522b\u5728\u5c5e\u6027\u503c\u6539\u53d8\u4e4b\u524d\u548c\u4e4b\u540e\u53d1\u9001\u901a\u77e5\u3002<\/li>\n<li>\u901a\u77e5\u89e6\u53d1\uff1a\u88ab\u89c2\u5bdf\u5bf9\u8c61\u5728\u63a5\u6536\u5230\u5c5e\u6027\u53d8\u5316\u7684\u901a\u77e5\u540e\uff0c\u4f1a\u901a\u77e5\u6240\u6709\u6ce8\u518c\u7684\u89c2\u5bdf\u8005\uff0c\u4ee5\u4fbf\u5b83\u4eec\u53ef\u4ee5\u6267\u884c\u76f8\u5e94\u7684\u64cd\u4f5c\u3002<\/li>\n<\/ul>\n<p>KVO\u7684\u672c\u8d28\u662f\u901a\u8fc7\u91cd\u5199\u88ab\u89c2\u5bdf\u5bf9\u8c61\u7684setter\u65b9\u6cd5\uff0c\u62e6\u622a\u5bf9\u5c5e\u6027\u7684\u8d4b\u503c\u64cd\u4f5c\uff0c\u5e76\u89e6\u53d1\u76f8\u5e94\u7684\u901a\u77e5\u673a\u5236\u3002\u901a\u8fc7\u8fd0\u884c\u65f6\u52a8\u6001\u751f\u6210\u5b50\u7c7b\uff0cKVO\u5b9e\u73b0\u4e86\u5bf9\u5c5e\u6027\u53d8\u5316\u7684\u76d1\u542c\u548c\u901a\u77e5\u529f\u80fd\uff0c\u4f7f\u89c2\u5bdf\u8005\u80fd\u591f\u53ca\u65f6\u83b7\u53d6\u88ab\u89c2\u5bdf\u5bf9\u8c61\u5c5e\u6027\u503c\u7684\u53d8\u5316\uff0c\u800c\u4e0d\u9700\u8981\u663e\u5f0f\u5730\u8f6e\u8be2\u6216\u624b\u52a8\u89e6\u53d1\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"KVO\u662f\u6307\u5728\u8f6f\u4ef6\u5f00\u53d1\u4e2d\u4e00\u79cd\u89c2\u5bdf\u8005\u6a21\u5f0f\u7684\u5b9e\u73b0\uff0c\u5b83\u5141\u8bb8\u5bf9\u8c61\u76d1\u542c\u5176\u4ed6\u5bf9\u8c61\u7279\u5b9a\u5c5e\u6027\u7684\u53d8\u5316\uff0c\u5e76\u5728\u5c5e\u6027\u503c\u53d1\u751f\u6539\u53d8\u65f6\u5f97\u5230\u901a\u77e5 [&hellip;]","protected":false},"author":1,"featured_media":30590,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[37],"tags":[480],"acf":[],"_links":{"self":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/30588"}],"collection":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/comments?post=30588"}],"version-history":[{"count":0,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/posts\/30588\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media\/30590"}],"wp:attachment":[{"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/media?parent=30588"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/categories?post=30588"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/docs.pingcode.com\/wp-json\/wp\/v2\/tags?post=30588"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}