NSInteger和decodeInteger:forKey:问题

Question

我有以下两种归档方法:

    - (void) encodeWithCoder: (NSCoder *) encoder {
    [encoder encodeObject:self.exercises forKey:@"exercises"];
    [encoder encodeObject:self.title forKey:@"title"];
    [encoder encodeObject:self.description forKey:@"description"];
    [encoder encodeInteger:self.idnum forKey:@"idnum"];
    [encoder encodeInteger:self.rating forKey:@"rating"];
    [encoder encodeInteger:self.frequency forKey:@"frequency"];
    NSLog(@"Encoding!");

}

- (id) initWithCoder: (NSCoder *) decoder {
    self.exercises =   [[decoder decodeObjectForKey:@"exercises"] retain];
    self.title =       [[decoder decodeObjectForKey:@"title"] retain];
    self.description = [[decoder decodeObjectForKey:@"description"] retain];
    self.idnum =       [[decoder decodeIntegerForKey:@"idnum"] retain];
    self.rating =      [[decoder decodeIntegerForKey:@"rating"] retain];
    self.frequency =   [[decoder decodeIntegerForKey:@"frequency"] retain];
    NSLog(@"Decoding!");
    return self;
}

标题:

    @interface Workout : NSObject{

    NSMutableArray *exercises; 
    NSString *title;
    NSString *description;
    NSInteger idnum;
    NSInteger rating;
    NSInteger frequency;
}

- (void) encodeWithCoder: (NSCoder *) encoder;
- (id) initWithCoder: (NSCoder *) decoder;

@property(nonatomic,retain) NSMutableArray *exercises; 
@property(nonatomic,retain) NSString *title;
@property(nonatomic,retain) NSString *description;
@property(nonatomic) NSInteger idnum;
@property(nonatomic) NSInteger rating;
@property(nonatomic) NSInteger frequency;
@end

看起来很简单.encodeInteger接受一个NSInteger,我传递给它,而decodeIntegerForKey返回一个NSInteger,但是我得到了这个奇怪的错误:

警告:无效的接收器类型'NSInteger'

并且当执行decodeIntegerForKey指令时,我得到一个exec错误访问.

为什么会这样？

Answer 1

发布的代码存在一些问题.第一:

self.idnum =       [[decoder decodeIntegerForKey:@"idnum"] retain];

该代码正在向NSInteger发送'retain'.虽然NSIntegers不是对象,但它们只是标量.这是非法的.只需使用它:

self.idnum =       [decoder decodeIntegerForKey:@"idnum"];

接下来,这段代码:

self.exercises =   [[decoder decodeObjectForKey:@"exercises"] retain];

过度保留,会导致泄漏.既然您宣布了以下练习:

@property(nonatomic,retain) NSMutableArray *exercises; 

"保留"意味着当您调用setter时,它会保留传入的值,然后将其粘贴到"exercise"实例变量中.你在调用setter之前保留,所以这是一个双重保留.

您可以通过将代码更改为:

exercises =   [[decoder decodeObjectForKey:@"exercises"] retain];

要么:

self.exercises =   [decoder decodeObjectForKey:@"exercises"];