UIDevice

UIDevice類別是題供iPhone/iPod touch有關的裝置資訊
此類別唯一實體可利用類別方法currentDevice來取得,  下列是可利用這個實體取得的資訊

1. 獨一無二的識別資訊(unique identifier)

@property (nonatomic, readonly, retain) NSString *uniqueIdentifier;

2. 作業系統OS

@property (nonatomic, readonly, retain) NSString *systemName;

3. OS Version

@property (nonatomic, readonly, retain) NSString *systemVersion;

4. model (iPhone or iPod touch or iPad etc)

@property (nonatomic, readonly, retain) NSString *model;

5. 裝置定向   (可利用orientation屬性取得)

@property (nonatomic, readonly) UIDeviceOrientation orientation;
可能的內容值如下
-UIDeviceOrientationUnknown
-UIDeviceOrientationPortrait
-UIDeviceOrientationPortraitUpsideDown
-UIDeviceOrientationLandscapeLeft
-UIDeviceOrientationLandscapeRight
-UIDeviceOrientationFaceUp(螢幕朝上)
-UIDeviceOrientationFaceDown(螢幕朝下)


6. 電池狀態 (透過batteryLevel取得目前電池電量等級)

@property (nonatomic, readonly) float batteryLevel;

取得的數值是介於0.0~1.0(完全充飽), 假設電池電量無法背叛斷出來, 此值會等於1.0


6-1 利用batteryState取得電池狀態

@property (nonatomic, readonly) UIDeviceBatteryState batteryState;

回傳值為下列之一
-UIDeviceBatteryStateUnknown (電池狀態無法判斷, 使用simulator會得到此結果)
-UIDeviceBatteryStateUnplugged (電池因為未接上電源而處於耗電狀態)
-UIDeviceBatteryStateCharging
-UIDeviceBatteryStateFull


6-2 電池狀態等級通知
任何物件都可以被當成觀察者來加入底下兩個通知
-UIDeviceBatteryLevelDidChangeNotification
  此通知會在電池電量等級有發生改變時被發送出來 , 發送頻率最多是每分鐘一次


-UIDeviceBatteryStateDidChangeNotification
  電池狀態有發生改變時被發送出來, 例如: 裝置正被連接到電源上


為了接收這些通知資訊, 須將屬性batteryMonitoringEnabled設為YES

Customization Navigation View

basic property of navigation

//取得Navigation實體

@property (nonatomic, readonly, retain) UINavigationItem *navigationItem

About afconvert

iPhone OS支援的音樂格式 （部份）
CAF：apple的core audio音樂格式（.caf）
ALAC ：apple不失真的音樂格式（.m4a）
AIFF：apple的音樂格式（.aif, .aiff）
AAC：itunes store音樂傳送時使用（.m4a）
MP3：（.mp3）

About AVAudioPlayer

There are many different ways to get an iPhone app to generate and record audio, but AVFoundation is the best compromise between simplicity and functionality

AVFoundation.framework : AVAudioPlayer, AVAudioRecorder

view switcher(三)-SwitchViewController

//

//  SwitchViewController.h

#import <UIKit/UIKit.h>

@class BlueViewController;

@class YellowViewController;

@interface SwitchViewController : UIViewController {

BlueViewController *_blueViewController;

YellowViewController *_yellowViewController;

}

@property (nonatomic, retain) BlueViewController *_blueViewController;

@property (nonatomic, retain) YellowViewController *_yellowViewController;

-(IBAction)switchViews:(id)sender;

@end

修改MainWindow.xib

按兩下MainWindow.xib開啓IB, 必須再建立用來表示root controller的實例; 因為IB程式庫沒有SwitchViewController, 所以必須加入一個view controller,再將其類別改為SwitchViewController

(圖一)將UIViewController拉到nib時所產生的view

接下來建立root controller的view, root controller的view將包含螢幕下方的一個工具列

之前我們將UIViewController拉到nib主視窗時, 產生了一個新視窗(如第一張圖), 要在此視窗為root controller(SwitchViewController)建立view

SwitchViewController主要任務是切換BlueView與YellowView, 所以必須有可以讓使用者改變檢視的方法, 所以在工具列增加一按鈕讓使用者切換檢視

從Library拖曳View到(圖一), Library拖曳Toolbar

更改button name 為 Switch Views

接著將動作與button連接

選擇MainWindow.xib的Switch View Controller, 選擇Inspector的Connections Inspector, 將switchViews方法連結至Toolbar的button (如下圖)

之前在SwitchViewControllerAppDelegate.h建立IBOutlet (_switchViewController), 因此應用程式可以連接到SwitchViewController的實例, 並在主要的應用程式視窗中加入sub view,..  所以必須在nib中將SwitchViewController實例連接到此IBOutlet

選擇Switch View Controller App Delegate, 選擇Inspector的Connections Inspector,將_switchViewController連接到SwitchViewController的實例, 如下圖

儲存nib, 開始編輯SwitchViewController.m

//  SwitchViewController.m

//  SwitchViewController

//

#import "SwitchViewController.h"

#import "BlueViewController.h"

#import "YellowViewController.h"

@implementation SwitchViewController

@synthesize _blueViewController;

@synthesize _yellowViewController;

-(IBAction)switchViews:(id)sender

{
//先檢查_yellowViewController的view之上層view是否為nil

if (self._yellowViewController.view.superview == nil) 

{
//檢察_yellowViewController是否被建立, 若尚未被建立, 則下列if成立 

if (self._yellowViewController == nil) 

{

YellowViewController *yellowController = [[YellowViewController alloc]

  initWithNibName:@"YellowView" bundle:nil];

self._yellowViewController =yellowController;

[yellowController release];

}

[_blueViewController.view removeFromSuperview];

[self.view insertSubview:_yellowViewController.view atIndex:0];

}

else {

if (self._blueViewController == nil) 

{

BlueViewController *blueController = [[BlueViewController alloc]

  initWithNibName:@"BlueView" bundle:nil];

self._blueViewController =blueController;

[blueController release];

}

[_yellowViewController.view removeFromSuperview];

[self.view insertSubview:_blueViewController.view atIndex:0];

}

}

- (void)viewDidLoad {

BlueViewController *blueController = [[BlueViewController alloc] 

  initWithNibName:@"BlueView" bundle:nil];

self._blueViewController = blueController;
//將藍色檢視加入成為根檢視的子檢視, 索引值為0表示此子檢視放在所有東西的最下層,
//如此可確保工具列永遠都看的見

[self.view insertSubview:blueController atIndex:0];

[blueController release];

    [super viewDidLoad];

}

- (void)didReceiveMemoryWarning {

    // Releases the view if it doesn't have a superview.

    [super didReceiveMemoryWarning];

if (self._blueViewController.view.superview == nil) 

{

self._blueViewController = nil;

}

else 

{

self._yellowViewController = nil;

}

}

- (void)viewDidUnload {

    [super viewDidUnload];

    // Release any retained subviews of the main view.

    // e.g. self.myOutlet = nil;

}

- (void)dealloc {

[_blueViewController release];

[_yellowViewController release];

    [super dealloc];

}

@end

將兩個檢視加入按鈕觸發動作

//

//  BlueViewController.h

#import <UIKit/UIKit.h>

@interface BlueViewController : UIViewController {

}

-(IBAction)blueButtonPressed;

@end

//

//  YellowViewController.h

#import <UIKit/UIKit.h>

@interface YellowViewController : UIViewController {

}

-(IBAction)yellowButtonPressed;

@end

將兩個檢視與 xib連結,  分別開啓BlueView.xib , YellowView.xib

ex: double click "BlueView.xib", select File's Owner, 按下command+4呼叫Identity Inspector

NSObject 改為 BlueViewController

更改view背景顏色為藍色

增加button, 連接blueButtonPressed, 除了連接IBAction, 還要將BlueViewController的View接口連接到nib中的view

YellowView的做法也與BlueView相同