如何在这个线程的中间更新UI？ [英] How do I update the UI in the middle of this thread?

问题描述

下面是一段代码，在我的应用程序的主线程的单独线程中运行。如何在每个按钮获取其缩略图之后更新UI？现在它不更新，直到整个方法完成。这些按钮已添加到UIScrollView。

Below is a block of code that runs in a separate thread from my app's main thread. How do I get the UI to update after each button gets its thumbnail? Right now it doesn't update until the whole method finishes. The buttons are already added to a UIScrollView.

（LotsGridButton只是一个具有一些额外属性的UIButton。）

(LotsGridButton is just a UIButton with some extra properties.)

- (void)fetchThumbnails {
    CCServer* server = [[CCServer alloc] init];
    for (int i=0; i<[buttons count]; i++) {
        LotsGridButton* button = [buttons objectAtIndex:i];     
        if (button.lot.thumbnail) continue;
        // load the thumbnail image from the server
        button.lot.thumbnail = [server imageWithPath:button.lot.thumbnailURL];
        [button setImage:button.lot.thumbnail forState:UIControlStateNormal];
    }
    [server release];
}

推荐答案

$ c> setImage：forState：，请查看 performSelectorOnMainThread：方法，例如：

In place of setImage:forState:, take a look at the performSelectorOnMainThread: method, e.g.:

[myButton performSelectorOnMainThread:@selector(setThumbnail:) withObject:[server imageWithPath:myButton.lot.thumbnailURL] waitUntilDone:NO];

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