在drawInRect:rect处崩溃，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，但当我们在实际的 iPhone 设备中运行它时，它在以下行崩溃：

[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，因为当我们运行时时间很短必须在本周五提交。看下面的解决方案： 必须drawInRect：对于单独的上下文在主线程上执行？

发生崩溃的部分位于 Sculpture.m 中的 viewDidLoad()

- (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();

}

提前一百万致谢...

Answer 1

您没有说明崩溃的具体位置，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。我的猜测是后一个是问题所在（获得正确的论点可能很棘手）并且无论如何都不是您想要的。所以将其更改为：

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