With iOS 9, you'll need a lot less free space on your phone to be able to install the upgrade. Now one may argue that running iOS 9 on an older device (like an iPhone 4S), isn't going to lead to a great experience — and that person would have a point. Having said that, I've run iOS 9 betas on an iPhone 5S, an iPhone 6, iPhone 6 Plus, an iPad Air and an iPad Air 2,and all performed extremely well.
第九代苹果操作系统手机安装更新软件内存占用空间小。现有人指出在老版苹果手机（如苹果4s）运行第九代操作系统时不能有很好的体验——这个人某种程度上说中了要点。基于这个评论，我在苹果5s。苹果6，苹果6+，iPad Air 和iPad Air 2都安装了第九代操作系统，无一例外，都运行得棒棒哒。

let's talk about the features.
现在我们就来聊一聊第九代苹果操作系统的特征吧。

Siri is everywhere...and she's good 
Siri (语言操作功能)无处不在，而且她真的很棒。

With iOS 9, Siri gets a big upgrade and she's a lot more like an actual assistant now. That's important because Siri is now featured throughout iOS 9.
第九代苹果操作系统较大升级了语音操作功能，她现在更像是一个真正的助手了。这一更新很重要因为现在整个第九代操作系统最大的特征就是语音操作系统啦。

Siri can answer contextual questions now, too. You can ask for a game score and then follow up by asking when the team plays again, without having to restate your question. This is awesome.
现在Siri也可以回答前后关联的问题啦。你可以问一场赛事的得分，之后还可以问这个队什么时候还会有比赛，而且还不用重述你的问题。棒，棒，棒！

Notes is new
记事本应用更新

Apple also overhauled the Notes app, making it a lot more robust. You can insert photos, draw with your finger, add maps, create lists and it supports rich-text features.
苹果同时也革新了记事本应用，使之更为灵活。你可以插入图片，用手指画画，创建列表，同时支持各种文本格式。

Apple News is here
苹果新闻应用来啦

Apple is getting a brand new app with iOS 9, and that's Apple News. Apple has already signed with a bunch of publishing partners and the app performs well and is a fast way of reading well-formatted news on your phone or tablet.
第九代操作系统新增了一个全新的应用——苹果新闻。苹果已经和一大批出版合作商签订条约，并且该应用运行得相当好，能够在苹果手机或平板上快速地阅读已经发布的新闻。

Performance and battery life
性能和电池寿命

There's a new Low Power Mode that will help you get the most out of your battery life.
第九代操作系统还有一个新的“低电量模式”，能够帮助你将电池电量发挥到极致。

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