在drawInRect：rect崩溃，我有解决方案但不知道如何？

Question

该应用程序在 iphone 模拟器上运行良好，但是当我们在实际的 iphone 设备上运行它时，它会在以下行崩溃：

[ucdView.image drawInRect:rect];

我已经搜索并找到了解决方案，但我不知道如何解决，因为时间很短，我们必须在本周五展示它。看下面的解决方案： Must drawInRect: for a separate context be executed on the main thread?

发生这种崩溃的部分是在 viewDidLoad() 中的 Sculpture.m 中

- (void)viewDidLoad{
[super viewDidLoad]; 

CLController = [[CoreLocationController alloc] init];
CLController.delegate = self;
[CLController.locMgr startUpdatingLocation];

currentLoc = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"redPin.png"]];

UIImage *ucdImage = [UIImage imageNamed:@"ucd.png"];
self.ucdView = [[UIImageView alloc] initWithImage:ucdImage];//creating a view for UCD image
ucdView.userInteractionEnabled = YES;

[self loadingFile];

UIScrollView *myScrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
[myScrollView setMinimumZoomScale:0.35];
[myScrollView setMaximumZoomScale:2.0];
myScrollView.clipsToBounds = YES;
myScrollView.bounces = YES;
myScrollView.contentOffset = CGPointMake(1400, 700);
[myScrollView setContentSize:CGSizeMake(ucdImage.size.width, ucdImage.size.height)];
[myScrollView setDelegate:self];
[myScrollView addSubview:ucdView];//adding ucd view to scroll view
[self.view addSubview:myScrollView]; // adding scrollview to self.view main view
[myScrollView release];


//Drawing The Line
UIGraphicsBeginImageContext(ucdView.frame.size);
CGRect rect = CGRectMake(0, 0, ucdView.frame.size.width, ucdView.frame.size.height);
[ucdView.image drawInRect:rect];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(context, 3.0);
CGContextSetStrokeColorWithColor(context, [UIColor blueColor].CGColor);
CGFloat dashArray[] = {2,0,2,2};
CGContextSetLineDash(context, 3, dashArray, 5);
CGContextMoveToPoint(context,[self longt_to_x:[[path_array objectAtIndex:0] doubleValue]],[self lat_to_y:[[path_array objectAtIndex:1] doubleValue]]);
int path_length = [path_array count];
for(int i = 2; i<path_length; i = i+2){
    CGContextAddLineToPoint(context,[self longt_to_x:[[path_array objectAtIndex:i] doubleValue]],[self lat_to_y:[[path_array objectAtIndex:i+1] doubleValue]]);
}
CGContextStrokePath(context);
ucdView.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

}

提前一百万谢谢...

Answer 1

您没有说崩溃的确切位置，但您已经使用UIGraphicsBeginImageContext 创建了一个图像上下文，然后使用CGBitmapContextCreate 创建了另一个图像上下文。我的猜测是后一个问题是问题（让论点正确可能很棘手），而且无论如何都不是你想要的。所以改成：

// Get the current drawing context which is the image context right now
CGContextRef context = UIGraphicsGetCurrentContext();