Slider的基本使用(ㄧ)

一個最基本的動態Slider的設定與使用，這是配合在iPad上Popover的設計用法。主要是使用一個Timer來當中斷，並檢查公共變數的值，來即時顯示變化。

Xcode版本4.5 & IOS6


1. 開一個iPad的專案

2. 設定StoryBoard，並加入一個Tool Bar及一個Label

3. 加入一個UIViewController，並將BarItem拉一個Segue到這個UIView

4.新增一個class 檔，對應到步驟三的新UIView

5. 對UIView上的Class指定成此到新增的Class檔

6. 對mainAppDelegate.h設定公共變數
#import <UIKit/UIKit.h>

@interface mainAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@property (nonatomic, retain)   NSMutableArray *globalData;

@end



7. 對mainAppDelegate.m設定
#import "mainAppDelegate.h"

@implementation mainAppDelegate

@synthesize globalData;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // Override point for customization after application launch.
    return YES;
}
...

8. 對主程式的mainViewController.h加入所需的變數
#import <UIKit/UIKit.h>
#import "mainAppDelegate.h"

@interface mainViewController : UIViewController

@property (weak, nonatomic) IBOutlet UILabel *valueLabel;

@property (nonatomic, retain) mainAppDelegate *appDelegate;

@property (nonatomic) NSTimer  *timer;

@property (nonatomic) NSNumber  *sliderValue;

- (void) showText;

@end

9. 對主程式的mainViewController.m加入所需的程式碼
#import "mainViewController.h"

@interface mainViewController ()

@end

#define TimeUnit 0.5 // 0.5sec

@implementation mainViewController

@synthesize sliderValue;
@synthesize timer;
@synthesize appDelegate;
@synthesize valueLabel;

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
   
    appDelegate = (mainAppDelegate *) [[UIApplication sharedApplication] delegate];
   
    appDelegate.globalData = [[NSMutableArray alloc] init];
   
    NSNumber *defaultValue = [NSNumber numberWithDouble:0.3];
   
    [appDelegate.globalData addObject:defaultValue];  //0

   
    [self  initTimer];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void) initTimer
{
   
    // nowTime = lastTime;
    if (timer == nil)
    {
        timer = [NSTimer scheduledTimerWithTimeInterval:TimeUnit target:self selector:@selector(showText) userInfo:nil repeats:YES];
    }
}

- (void) showText
{
    sliderValue = [appDelegate.globalData objectAtIndex:0];

    valueLabel.text= [NSString stringWithFormat:@"Value = %2.3f",[sliderValue floatValue]] ;
   
}


@end

10.對Slider所在的UIView作設定，先針對SliderViewController.h
#import <UIKit/UIKit.h>
#import "mainViewController.h"
#import "mainAppDelegate.h"

@interface SliderViewController : UIViewController

@property (nonatomic, retain) mainAppDelegate *appDelegate;

@property (nonatomic) UISlider  *mySlider;

@property (nonatomic) float myValue;

-(void) controlValueChanged;

@end

11.最後對SliderViewController. m加入控制碼
#import "SliderViewController.h"

@interface SliderViewController ()

@end

@implementation SliderViewController

@synthesize appDelegate;
@synthesize mySlider;
@synthesize myValue;

float  lastvalue=0.5;

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

//特別說明，因為Popover再一次指定後，會重複執行此處。

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
   
    appDelegate = (mainAppDelegate *)[[UIApplication sharedApplication] delegate];
   
    mySlider = [[UISlider alloc] initWithFrame:CGRectMake(0, 0, 300, 50)];
    [mySlider addTarget:self action:@selector(controlValueChanged) forControlEvents:UIControlEventValueChanged];
   
    mySlider.minimumValue = 0;
    mySlider.maximumValue = 3;
    mySlider.continuous = YES;
   
    // voiceSlider.value = 0.5;  // 此種設定會讓Slider不能動
    [mySlider setValue:lastvalue]; //只可以用此法，
   
    [self.view addSubview:mySlider];
   
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void) controlValueChanged
{
    myValue = mySlider.value;
   
    NSNumber *number = [NSNumber numberWithFloat:myValue];
   
    [appDelegate.globalData replaceObjectAtIndex:0 withObject:number];
   
    lastvalue = myValue;
}


@end


12. 執行結果，Label會即時顯示Slider上的變化。