有一个程序编译,但然后退出,返回上述错误信息。线程1:EXC_BAD_ACCESS(代码= 13,地址= 0x0)
这里是0 objc_msgSend日志;都谈到了线出现错误消息上:
libobjc.A.dylib`objc_msgSend:
0x7fff8c9b7e80: testq %rdi, %rdi
0x7fff8c9b7e83: je 0x00007fff8c9b7eb0 ; objc_msgSend + 48
0x7fff8c9b7e85: testb $1, %dil
0x7fff8c9b7e89: jne 0x00007fff8c9b7ec7 ; objc_msgSend + 71
0x7fff8c9b7e8c: movq (%rdi), %r11
0x7fff8c9b7e8f: pushq %rax
0x7fff8c9b7e90: movq 16(%r11), %r10
0x7fff8c9b7e94: movl %esi, %eax
0x7fff8c9b7e96: andl (%r10), %eax // error message arrow appears on this line
0x7fff8c9b7e99: movq 16(%r10,%rax,8), %r11
0x7fff8c9b7e9e: incl %eax
0x7fff8c9b7ea0: testq %r11, %r11
0x7fff8c9b7ea3: je 0x00007fff8c9b7edb ; objc_msgSend + 91
0x7fff8c9b7ea5: cmpq (%r11), %rsi
0x7fff8c9b7ea8: jne 0x00007fff8c9b7e96 ; objc_msgSend + 22
0x7fff8c9b7eaa: popq %rax
// Rest left out; no error messages
的main.m:
#import <Foundation/Foundation.h>
#import "Budget.h"
#import "Transaction.h"
#import "CashTransaction.h"
#import "CreditCardTransaction.h"
int main(int argc, const char * argv[])
{
Budget *europeBudget = [Budget new];
[europeBudget createBudget:1000.00 withExchangeRate:1.2500];
Budget *englandBudget = [Budget new];
[englandBudget createBudget:2000.00 withExchangeRate:1.5000];
NSMutableArray *transactions = [[NSMutableArray alloc]initWithCapacity:10];
Transaction *aTransaction;
for (int n=1; n < 2; n++) {
[aTransaction createTransaction:n * 100 forBudget:europeBudget];
[transactions addObject:aTransaction];
aTransaction = [CashTransaction new];
[aTransaction createTransaction:n * 100 forBudget:englandBudget];
[transactions addObject:aTransaction];
}
int n = 1;
while (n < 4) {
[aTransaction createTransaction:n * 100 forBudget:europeBudget];
[transactions addObject:aTransaction];
aTransaction = [CreditCardTransaction new];
[aTransaction createTransaction:n * 100 forBudget:englandBudget];
[transactions addObject:aTransaction];
n++;
}
for (Transaction * aTransaction in transactions) {
[aTransaction spend];
}
return 0;
}
Transaction.h
进口@class预算;
@interface Transaction : NSObject
{
Budget *budget;
double amount;
}
- (void) createTransaction:(double)theAmount forBudget:(Budget*) aBudget;
- (void) spend;
- (void)trackSpending: (double) theAmount;
@end
Transaction.m
#import "Transaction.h"
#import "Budget.h"
@implementation Transaction
- (void) createTransaction:(double)theAmount forBudget:(Budget*) aBudget
{
budget = aBudget;
amount = theAmount;
}
- (void) spend
{
// Fill in the method in subclasses
}
-(void)trackSpending: (double) theAmount
{
NSLog(@"You are about to spend another %.2f", theAmount);
}
@end
纠正我,如果我错了,但0x0是NULL为十六进制。我想你是在传递一个空对象。 – CodaFi 2012-03-24 18:13:44
认为它可能位于NSMutableArray对象中,但找不到它。已经添加了main.m文件供您阅读。 – pdenlinger 2012-03-24 18:26:40
发送消息给一个无对象是完全没问题的。它返回零,编译器将其转换为函数的返回类型。 (这是一个问题,如果你的返回类型是NSRect,但是新版本的SDK可以正确处理,正如我所记得的那样。)objc_messageSend中的崩溃通常意味着你正在向释放的对象发送消息。 – davehayden 2012-03-24 18:29:07