在iOS開發上
若是從檔案讀取一些資料,想必會用到
- NSMutableArray
- NSMutableDictionary
這二個類別
Mutable是可變動的意思,所以建立之後還可以變動
NSMutableArray的話存取方式採用序號來存取值
而NSMutableDictionary採用自訂的鍵值(key)來存取值(value)
二者可以互相混用,NSMutableDictionary裡面有NSMutableArray
或是NSMutableArray裡面包含NSMutableDictionary (就像本次範例)
使用initWithContentsOfFile: 方法來載入plist
https://developer.apple.com/library/ios/#documentation/Cocoa/Reference/Foundation/Classes/NSData_Class/Reference/Reference.html#//apple_ref/occ/instm/NSData/initWithContentsOfFile:
NSMutableArray要取得值使用objectAtIndex 方法
https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/NSArray.html#//apple_ref/occ/instm/NSArray/objectAtIndex:
NSMutableDictionary要取得值使用objectForKey方法
https://developer.apple.com/library/ios/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/Reference/Reference.html#//apple_ref/occ/instm/NSDictionary/objectForKey:
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提外話一下
如果有寫過php的話
他的概念和php的array有一點點類似
http://php.net/manual/en/language.types.array.php
而NSMutableArray類似於
<?php
$array = array("foo", "bar");
var_dump($array);
?>
螢幕輸出:
array(4) { [0]=> string(3) "foo" [1]=> string(3) "bar" }
而NSMutableDictionary類似於
<?php
$array = array(
"foo" => "bar",
"bar" => "foo"
);
var_dump($array);
?>
螢幕輸出:
array(4) { ["foo"]=> string(3) "bar" ["bar"]=> string(3) "foo" }
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建立一個專案,在專案上按右鍵New File:
新增一個Property List,名叫article.plist
article.plist原始碼如下
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN""http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>
<dict>
<key>title</key>
<string>title 01</string>
<key>content</key>
<string>content 01</string>
</dict>
<dict>
<key>title</key>
<string>title 02</string>
<key>content</key>
<string>content 02</string>
</dict>
<dict>
<key>title</key>
<string>title 03</string>
<key>content</key>
<string>content 03</string>
</dict>
</array>
</plist>
做一個Button出來,綁定TestpList_btn_onClick方法,該方法如下
- (IBAction)TestpList_btn_onClick:(id)sender {
// 取得專案中內建的pList路徑
NSString *path = [[NSBundlemainBundle] pathForResource:@"article"ofType:@"plist"];
NSLog(@"pList Path: %@\n", path);
// 將pList中的資料從檔案載入
NSMutableArray *data_pList = [[NSMutableArrayalloc] initWithContentsOfFile:path];
for(NSInteger i=0;i<[data_pList count]; i++)
{
NSIndexPath *indexPath=[NSIndexPathindexPathForRow:i inSection:0];
NSString *title = [[data_pList objectAtIndex:indexPath.row] objectForKey:@"title"];
NSString *content = [[data_pList objectAtIndex:indexPath.row] objectForKey:@"content"];
NSLog(@"Index: %i Title: %@ Content: %@\n", i, title, content);
}
}
然後運行程式,按下按鈕之後,在Log這邊得到以下結果:
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順便補充在iOS上的printf裡的格式跟一般的C語言不同
https://developer.apple.com/library/ios/#documentation/Cocoa/Conceptual/Strings/Articles/formatSpecifiers.html#//apple_ref/doc/uid/TP40004265-SW1
string 要使用 %@
integer 要使用 %i 而不是 %d
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