先看下面一个例子
#import <UIKit/UIKit.h> #import "AppDelegate.h" @interface Something : NSObject - (void)doWithError:(NSError **)outError; @end @implementation Something - (void)doWithError:(NSError **)outError
{
@autoreleasepool
{
*outError = [NSError errorWithDomain:@"Emergency" code:999 userInfo:nil];
}
} @end int main(int argc, const char *argv[])
{
@autoreleasepool
{
NSError *error = nil;
// Sometimes EXC_BAD_ACCESS when return from this method.
[[[Something alloc] init] doWithError:&error]; // At this point, the main thread gives EXC_BAD_ACCESS.
NSLog(@"%@", error);
}
return 0;
}
在NSLog输出的时候会EXC_Bad_ACCESS
正确写法应该是这样：
@interface Something : NSObject - (void)doWithError:(NSError **)outError; @end @implementation Something - (void)doWithError:(NSError **)outError
{
NSError *error = nil;
@autoreleasepool
{
error = [NSError errorWithDomain:@"Emergency" code:999 userInfo:nil];
// Do something
}
if(error)
{
*outError = error;
}
} @end int main(int argc, char * argv[])
{
@autoreleasepool
{
NSError *__autoreleasing error = nil; [[[Something alloc] init] doWithError:&error]; // At this point, the main thread gives EXC_BAD_ACCESS.
NSLog(@"%@", error); int a = 1;
++a;
}
return 0;
}