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我目前正在学习objective-c，一直到归档，都被编码和解码困住了。

这是我的代码。

 #import <Foundation/Foundation.h>

    @interface Foo : NSObject<NSCoding>

    @property (copy, nonatomic) NSString *strVal;
    @property int intVal;
    @property float floatVal;

    @end

    #import "Foo.h"

@implementation Foo

@synthesize intVal, floatVal, strVal;

-(void) encodeWithCoder: (NSCoder *) encoder
{
    [encoder encodeObject: strVal forKey: @"test1"];
    [encoder encodeInt: intVal forKey: @"test2"];
    [encoder encodeFloat: floatVal forKey: @"test3"];
}

-(id) initWithCoder: (NSCoder *) decoder
{
    strVal = [decoder decodeObjectForKey: @"test1"];
    intVal = [decoder decodeIntForKey: @"test2"];
    floatVal = [decoder decodeFloatForKey: @"test3"];

    return self;
}

@end


    #import "Foo.h"

    int main (int argc, const char * argv[])
    {

        @autoreleasepool {
            Foo *myFoo1 = [[Foo alloc] init];
            Foo *myFoo2;

            [myFoo1 setStrVal : @"bill"];
            [myFoo1 setIntVal : 2];
            [myFoo1 setFloatVal: 3.4];

            [NSKeyedArchiver archiveRootObject: myFoo1 toFile: @"foo.arch"];

            myFoo2 = [NSKeyedUnarchiver unarchiveObjectWithFile: @"foo.arch"];

            NSLog(@"%@", [myFoo2 strVal]);
        }
        return 0;
    }

解码适用于 int 和 float，但是当我尝试解码 NSString 对象时。我收到以下错误，但我对此一无所知...

线程 1：程序接收到的信号：EXC_BAD_ACESS"

GNU gdb 6.3.50-20050815 (Apple version gdb-1708) (Mon Aug 15 16:03:10 UTC 2011)
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Current language:  auto; currently objective-c
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4

2 回答 2

2

-initWithCoder:是一个初始化方法，您必须[super init]在设置对象之前调用它。请参阅 Apple 的“ Archives and Seralizations Programming Guide ”中的示例。

于 2013-04-07T03:21:41.503 回答
0

你在用ARC吗？

无论如何，您应该复制所有字符串 ( strValue = [[decoder decodeObjectForKey:@"test1"] copy];)，以保持对它们的不可变引用。否则，它们可能会在您的背后发生变化或消失，事情会变得很糟糕（就像您所看到的那样）。

另外，就像@一二三说的，别忘了self = [super init];.

于 2013-04-07T05:37:06.457 回答