1 前言
本章作為入門，我們將介紹介紹一下，能使用GCD執行UI操作。

2 代碼實例
ZYViewController.h

 

[plain]
#import <UIKit/UIKit.h> 
 
@interface ZYViewController : UIViewController 
 
@end 

#import <UIKit/UIKit.h>

@interface ZYViewController : UIViewController

@end
ZYViewController.m

 

[plain]
 (void)viewDidLoad 
{ 
    [super viewDidLoad]; 
    //dispatch_queue_t:一個調度隊列是一個輕量級的對象,你的應用程序提交模塊的後續執行。獲得主隊列 
    dispatch_queue_t mainQueue = dispatch_get_main_queue(); 
    /* 
     提交一個塊為異步執行在一個調度隊列,並立即返回。 
     隊列 
     　　隊列來提交塊。隊列是由系統保留直到塊已經運行到完成。該參數不能為空。 
     塊 
     　　塊提交到目標調度隊列。這個函數執行塊復制和釋放調用者。該參數不能為空。 
     */ 
    dispatch_async(mainQueue, ^(void) 
    { 
        [[[UIAlertView alloc] initWithTitle:@"GCD" 
                              message:@"GCD is amazing!" 
                              delegate:nil cancelButtonTitle:@"OK" 
                              otherButtonTitles:nil, nil] show]; 
    }); 
} 

- (void)viewDidLoad
{
    [super viewDidLoad];
    //dispatch_queue_t:一個調度隊列是一個輕量級的對象,你的應用程序提交模塊的後續執行。獲得主隊列
    dispatch_queue_t mainQueue = dispatch_get_main_queue();
    /*
     提交一個塊為異步執行在一個調度隊列,並立即返回。
     隊列
     　　隊列來提交塊。隊列是由系統保留直到塊已經運行到完成。該參數不能為空。
     塊
     　　塊提交到目標調度隊列。這個函數執行塊復制和釋放調用者。該參數不能為空。
     */
    dispatch_async(mainQueue, ^(void)
    {
        [[[UIAlertView alloc] initWithTitle:@"GCD"
                              message:@"GCD is amazing!"
                              delegate:nil cancelButtonTitle:@"OK"
                              otherButtonTitles:nil, nil] show];
    });
}
ZYAppDelegate.h

 

[plain]
#import <UIKit/UIKit.h> 
 
@class ZYViewController; 
 
@interface ZYAppDelegate : UIResponder <UIApplicationDelegate> 
 
@property (strong, nonatomic) UIWindow *window; 
 
@property (strong, nonatomic) ZYViewController *viewController; 
 
@end 

#import <UIKit/UIKit.h>

@class ZYViewController;

@interface ZYAppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

@property (strong, nonatomic) ZYViewController *viewController;

@end
ZYAppDelegate.m

 

[plain] view plaincopyprint?//聲明結構體AlertViewData 
typedef struct{ 
    char *title; 
    char *message; 
    char *cancelButtonTitle; 
} AlertViewData; 
 
 
@implementation ZYAppDelegate 
 
//C函數 
void displayAlertView(void *paramContext){ 
    AlertViewData *alertData = (AlertViewData *)paramContext; NSString *title = 
    [NSString stringWithUTF8String:alertData->title]; 
    NSString *message = 
    [NSString stringWithUTF8String:alertData->message]; 
    NSString *cancelButtonTitle = 
    [NSString stringWithUTF8String:alertData->cancelButtonTitle]; 
    [[[UIAlertView alloc] initWithTitle:title message:message delegate:nil cancelButtonTitle:cancelButtonTitle 
                      otherButtonTitles:nil, nil] show]; 
    free(alertData); 
} 
 
- (void)dealloc 
{ 
    [_window release]; 
    [_viewController release]; 
    [super dealloc]; 
} 
 
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{ 
    //獲得主線程隊列 
    dispatch_queue_t mainQueue = dispatch_get_main_queue(); 
     
    AlertViewData *context = (AlertViewData *) malloc(sizeof(AlertViewData)); 
    if (context != NULL){ 
        context->title = "GCD"; 
        context->message = "GCD is amazing."; 
        context->cancelButtonTitle = "OK"; 
        dispatch_async_f(mainQueue, 
                         (void *)context, 
                         displayAlertView); 
        //輸出當前線程 
        NSLog(@"Current thread = %@", [NSThread currentThread]); 
        //輸出主線程 
        NSLog(@"Main thread = %@", [NSThread mainThread]); 
    } 
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease]; 
    self.window.backgroundColor = [UIColor whiteColor]; 
     
    // Override point for customization after application launch. 
    self.viewController = [[[ZYViewController alloc] initWithNibName:@"ZYViewController" bundle:nil] autorelease]; 
    self.window.rootViewController = self.viewController; 
    [self.window makeKeyAndVisible]; 
    return YES; 
} 

//聲明結構體AlertViewData
typedef struct{
    char *title;
    char *message;
    char *cancelButtonTitle;
} AlertViewData;

@implementation ZYAppDelegate

//C函數
void displayAlertView(void *paramContext){
    AlertViewData *alertData = (AlertViewData *)paramContext; NSString *title =
    [NSString stringWithUTF8String:alertData->title];
    NSString *message =
    [NSString stringWithUTF8String:alertData->message];
    NSString *cancelButtonTitle =
    [NSString stringWithUTF8String:alertData->cancelButtonTitle];
    [[[UIAlertView alloc] initWithTitle:title message:message delegate:nil cancelButtonTitle:cancelButtonTitle
                      otherButtonTitles:nil, nil] show];
    free(alertData);
}

- (void)dealloc
{
    [_window release];
    [_viewController release];
    [super dealloc];
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    //獲得主線程隊列
    dispatch_queue_t mainQueue = dispatch_get_main_queue();
   
    AlertViewData *context = (AlertViewData *) malloc(sizeof(AlertViewData));
    if (context != NULL){
        context->title = "GCD";
        context->message = "GCD is amazing.";
        context->cancelButtonTitle = "OK";
        dispatch_async_f(mainQueue,
                         (void *)context,
                         displayAlertView);
        //輸出當前線程
        NSLog(@"Current thread = %@", [NSThread currentThread]);
        //輸出主線程
        NSLog(@"Main thread = %@", [NSThread mainThread]);
    }
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];
    self.window.backgroundColor = [UIColor whiteColor];
   
    // Override point for customization after application launch.
    self.viewController = [[[ZYViewController alloc] initWithNibName:@"ZYViewController" bundle:nil] autorelease];
    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];
    return YES;
}
運行結果

 
 

控制台結果

2013-05-10 10:59:21.871 GCDExcuteUITest[1661:c07] Current thread = <NSThread: 0x7113d00>{name = (null), num = 1}

2013-05-10 10:59:21.872 GCDExcuteUITest[1661:c07] Main thread = <NSThread: 0x7113d00>{name = (null), num = 1}