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我想延迟方法的调用，直到其他代码首先完成。

这是一个按钮触发的动作。用户扫描条形码。我希望在调用其他方法之前完成它：[self performSelector:@selector(otherMethod:) withObject:nil afterDelay:0.5]; 我尝试使用延迟，但这不好且不可预测。

    - (IBAction) scanButtonTapped
{
    NSLog(@"TBD: scan barcode here...");

    // ADD: present a barcode reader that scans from the camera feed
    ZBarReaderViewController *reader = [ZBarReaderViewController new];
    reader.readerDelegate = self;
    reader.supportedOrientationsMask = ZBarOrientationMaskAll;

    ZBarImageScanner *scanner = reader.scanner;
    // TODO: (optional) additional reader configuration here

    // EXAMPLE: disable rarely used I2/5 to improve performance
    [scanner setSymbology: ZBAR_I25
                   config: ZBAR_CFG_ENABLE
                       to: 0];

    // present and release the controller
    [self presentModalViewController: reader
                            animated: YES];

    [self performSelector:@selector(otherMethod:) withObject:nil afterDelay:0.5];


}
4

2 回答 2

3

也许您需要使用委托方法

- (void) imagePickerController:(UIImagePickerController*)picker didFinishPickingMediaWithInfo:(NSDictionary*)info
{
   //call other method here
}

我假设您正在使用 ZBar 库

于 2013-09-18T10:20:30.280 回答
1

您没有显示您的扫描代码，但我认为您需要在扫描完成（成功或其他方式）时传递一个块以调用

想象一下扫描方法是这样的：

- (void)scanBarCodeWithCompletionBlock:^(BOOL successfulScan)completionBlock {

    if (do the scan) {
        completionBlock(YES);
    } else {
        completionBlock(NO);
    }
}

您可能希望通过属性将完成块传递给扫描仪代码，并根据需要传递和调用它：

ZBarImageScanner *scanner = reader.scanner;
scanner.completionBlock = ^(BOOL successfulScan) {
    if (!successfulScan) {
         initiateMoaningSequence();
    }
};
于 2013-09-18T10:32:46.367 回答