在设备上运行时出现EXC_ARM_DA_ALIGN错误 [英] EXC_ARM_DA_ALIGN error when running on a device

问题描述

为什么这个代码在模拟器上运行并在真实设备上崩溃？

Why is this code running on the simulator and crashing on a real device?

我有一个非常简单的代码，它绘制了一个圆圈。代码子类 UIView 并在Simulator上运行正常（适用于iOS 5.1和iOS 6.0）。

I have a very simple code that draws a circle. The code subclasses UIView and runs fine on the Simulator (both for iOS 5.1 and iOS 6.0).

Circle.h

#import <UIKit/UIKit.h>

@interface Circle : UIView

@end

Circle.m

#import "Circle.h"

@implementation Circle

-(CGPathRef) circlePath{
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path addArcWithCenter:self.center radius:10.0 startAngle:0.0 endAngle:360.0 clockwise:YES];
    return path.CGPath;
}

- (void)drawRect:(CGRect)rect
{
    CGPathRef circle = [self circlePath];

    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGContextAddPath( ctx, circle );
    CGContextStrokePath(ctx);
}

@end

当我尝试执行运行iOS 5.1.1的iPad2上的代码我在 CGContextAddPath（ctx上）收到错误（ EXC_BAD_ACCESS（代码= EXC_ARM_DA_ALIGN，地址= 0x31459241）） circle）; line。

When I try to execute the code on an iPad2 running iOS 5.1.1 I get an error ( EXC_BAD_ACCESS(code=EXC_ARM_DA_ALIGN,address=0x31459241) ) on the CGContextAddPath( ctx, circle ); line.

我不知道问题是什么。任何人都可以指出我正确的方向来解决这个问题吗？

I have not a clue of what the problem is. Can anyone point me in the right direction to solve this issue?

推荐答案

这是因为 CGPath 您要返回的是由 circlePath 方法中创建的自动释放 UIBezierPath 所有。当您添加路径对象时， UIBezierPath 已被释放，因此返回的指针指向无效的内存。您可以通过返回 UIBezierPath 本身来修复崩溃：

This is because the CGPath you are returning is owned by the autoreleased UIBezierPath created in the circlePath method. By the time you are adding the path object the UIBezierPath has been released, so the returned pointer is pointing to invalid memory. You can fix the crash by returning the UIBezierPath itself:

-(UIBezierPath *)circlePath {
    UIBezierPath *path = [UIBezierPath bezierPath];
    [path addArcWithCenter:self.center radius:10.0 startAngle:0.0 endAngle:360.0 clockwise:YES];
    return path;
}

然后使用以下方式绘制：

Then draw using:

CGContextAddPath( ctx, circle.CGPath );

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