June 2013
Intermediate to advanced
360 pages
6h 50m
Chinese
Content preview from COCOA學習手冊--使用OBJECTIVE-C第三版
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Foundation 框架
|
51
字元編碼
大多數情況下，你在處理文字時會想要使用
NSUTF8StringEncoding
—它是目前
最常用來表示人類語言的方式，並且具有 ASCII（美國資訊交換標準碼）兼容的
額外好處。UTF-8 也很有用，因為它能夠表示 Unicode 標準裡的任何碼位（code
point，或稱編碼位置），Unicode 標準幾乎包含全世界所有人類語言的每一個書寫
字元，甚至不只如此。然而，的確還有其他編碼標準存在，並且值得你更仔細地
瞭解它們，因為你的程式碼有一天可能得處理它們，一項很不錯的入門資訊就是
關於字元編碼（character encoding）的 Wikipedia 文章（
http://bit.ly/TFo0Ty
）。
這種字串載入方法（把檔案載入成資料，再把資料轉換成字串）並不是載
入字串最有效率的方法，但我們把它當作說明如何使用
NSData
類別的範
例。從磁碟載入字串比較直接的方法就是利用
NSString
的
stringWithCon
tentsOfFile:encoding:error:
方法，該方法透過一個步驟即可從磁碟載
入該字串。
你能夠以類似方法把
NSData
物件寫到磁碟—透過
writeToFile:atomically:
方法。這
個方法接受包含路徑的字串以及一個
BOOL
值，指明該寫入是否應該以
不可切割
的方式
（
atomically
）完成—換言之，要嘛完全成功，不然就徹底失敗。假如這個旗標被設成
YES
，
NSData
將位元組寫到暫存檔，然後在完成時讓它就定位 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.