小编swa*_*rma的帖子

我在[alert show]行上获得了EXC_BAD_ACCESS.

为什么我得到这个？

 alert = [[UIAlertView alloc]initWithTitle:@"Application Alert" message:@"all date popup" delegate:self cancelButtonTitle:nil otherButtonTitles:@"Update",nil];

 [alert show]; //EXC_BAD_ACCESS on this line

我从下面的代码下载多个图像并保存到数据库.但对于一些图像,我得到低于错误.

错误:ImageIO:PNG无效距离太远错误:ImageIO:PNG错误数据检查

dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);                               
dispatch_async(queue, ^{
    NSString *imgStr = [dict  objectForKey:@"image"];                  
    imgStr = [imgStr stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
    NSData *imgData = [NSData dataWithContentsOfURL:[NSURL URLWithString:imgStr]];
    UIImage *image = [UIImage imageWithData:imgData];

    dispatch_sync(dispatch_get_main_queue(), ^{
       mYImageView.image = image;
    });
});

如何检查存储的图像是否有效,所以我可以再次下载图像？