代码之家 › 专栏 › 技术社区 › tadejsv

NSthread上的图像视图未更新

nsthread ios cocoa objective-c iphone

3

tadejsv · 技术社区 · 14 年前

我正在尝试制作一个测试应用程序来测量线程的性能。但是,我尝试在线程上将图像设置为ImageView,但它没有更新。实际上,甚至没有调用方法setImage1和setImage2。有什么想法吗? 查看代码了解详细信息

#import "UntitledAppDelegate.h"
#import <QuartzCore/QuartzCore.h>

@implementation UntitledAppDelegate

@synthesize window, imageView1, imageView2, label1, label2, label0;

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{            
    [window makeKeyAndVisible];
    return YES;
}

-(IBAction) startSeparate:(id) sender
{
 imageView1.image = imageView2.image = nil;
 double prev;

    start = prev = CACurrentMediaTime(); 
 [self setImage1];
 label1.text = [NSString stringWithFormat:@"%.10g", CACurrentMediaTime() - prev];

 prev = CACurrentMediaTime();  
 [self setImage2];
 label2.text = [NSString stringWithFormat:@"%.10g", CACurrentMediaTime() - prev];
}

-(IBAction) startThreaded:(id) sender
{
 imageView1.image = imageView2.image = nil;
 double prev;

 NSThread *t1 = [[NSThread alloc] init];
 [t1 start];
 NSThread *t2 = [[NSThread alloc] init];
 [t2 start];

    start = prev = CACurrentMediaTime(); 
    //This doesn't work
    //[self performSelector:@selector(setImage1) onThread:t1 withObject:nil waitUntilDone:NO];

    //But this does
 [self performSelectorInBackground:@selector(setImage1) withObject:nil];

 label1.text = [NSString stringWithFormat:@"%.10g", CACurrentMediaTime() - prev];

 prev = CACurrentMediaTime();  
 //This doesn't work
    //[self performSelector:@selector(setImage2) onThread:t2 withObject:nil waitUntilDone:NO];

    //But this does
 [self performSelectorInBackground:@selector(setImage2) withObject:nil];

 label2.text = [NSString stringWithFormat:@"%.10g", CACurrentMediaTime() - prev];
}

-(void) setImage1
{
 NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 UIImage *image1 = [UIImage imageNamed:@"bird.png"];
 imageView1.image = image1;
 [self pictureDone];
 [pool drain];
}

-(void) setImage2
{
 NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
 UIImage *image2 = [UIImage imageNamed:@"bird.png"];
 imageView2.image = image2;
 [self pictureDone];
 [pool drain];
}

-(void) pictureDone
{
 done++;
 NSLog(@"%i", done);
 if (done == 2) {
  label0.text = [NSString stringWithFormat:@"%.10g", CACurrentMediaTime() - start];
  done = 0;
 }
}
@end

2 回复 | 直到 14 年前

1

3

tia 14 年前

技术上, NSThread 本身不会自动创建运行循环,然后 performSelector:onThread 如果你只是用这种方式创建线程,就不会工作。

2

5

jmans 14 年前

从不从后台线程更改当前显示的uiview中的任何内容。您可能会遇到上百万种不同的同步问题。在后台线程中下载图像,然后在主线程上调用另一个方法(从后台线程)以实际更新uiImageView

performSelectorOnMainThread:...

对于方法未运行的问题,请尝试以下方法:

[self performSelectorInBackground:@selector(setImage2:) withObject:nil];

(在setImage2后添加冒号)。

另外,我不认为这两个nsthread对象(T1和T2)是必要的,它们也可能造成内存泄漏。