IOS多线程 - 使用线程加载一张图片 - NSThread(1)

更新UI的操作在IOS中其实和在Android中是一致的，都是不能在主线程中执行比较耗时的操作，所以需要开启新线程去做这些操作，以免阻塞主线程，当新线程中的操作完成之后，调用主线程来更新UI。下面就是一个这样的例子：

1、声明ImageView控件

1 #import <UIKit/UIKit.h>

2 

3 @interface DemoDispatchQueueViewController : UIViewController

4 @property(nonatomic,strong) UIImageView *imageView;

5 @end

2、完成功能

 1 #import "DemoDispatchQueueViewController.h"

 2 

 3 @interface DemoDispatchQueueViewController ()

 4 

 5 @end

 6 

 7 @implementation DemoDispatchQueueViewController

 8 @synthesize imageView;

 9 - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil

10 {

11     self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];

12     if (self) {

13     }

14     return self;

15 }

16 

17 - (void)viewDidLoad

18 {

19     [super viewDidLoad];

20     // Do any additional setup after loading the view.

21     self.title = @"GCD Demo";

22     

23     self.imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 10, 300, 380)];

24     

25     self.imageView.contentMode = UIViewContentModeScaleToFill;

26     

27     [self.view addSubview:imageView];

28     

29     [NSThread detachNewThreadSelector:@selector(loadImageByUrl:) toTarget:self withObject:@"http://image.rayliimg.cn/0008/2009-01-15/images/2009115135825184.jpg"]; 30     

31 }

32 

33 -(void) loadImageByUrl:(NSString *) imageUrl

34 {

35     NSLog(@"url is :%@",imageUrl);

36     NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:imageUrl]];

37     UIImage *image = [UIImage imageWithData:data];

38     

39     if(image != nil){

40  [self performSelectorOnMainThread:@selector(setImage:) withObject:image waitUntilDone:YES]; 41     }else{

42         NSLog(@"无法载入相应的图片");

43     }

44 }

45 -(void) setImage:(UIImage*) image{

46     [self.imageView setImage:image];

47 }

48 

49 

50 - (void)didReceiveMemoryWarning

51 {

52     [super didReceiveMemoryWarning];

53     // Dispose of any resources that can be recreated.

54 }

55 

56 @end

 

 转自 http://www.cnblogs.com/xinye/archive/2013/03/31/2991190.html