objective-c - 在类型 y 的对象上找不到属性 x

Question

新手，正在研究可编程计算器。

在模型类的接口中CalculatorBrain，我声明

@property (nonatomic, strong) NSMutableArray *whatHappenedSinceLastClear;  

然后在实现中我也声明

-(NSMutableArray *)whatHappenedSinceLastClear
{
if(!_whatHappenedSinceLastClear) _whatHappenedSinceLastClear = [[NSMutableArray alloc] init];
return _whatHappenedSinceLastClear;
}

接着

-(double)runProgram:(id)whatHappenedSinceLastClear
{
NSMutableArray *mutableCopyOfWhatHappenedSinceLastClear;
if ([program isKindOfClass:[NSArray class]]) {
    mutableCopyOfWhatHappenedSinceLastClear = [whatHappenedSinceLastClear mutableCopy];
}
return [self popOffProgramStack:mutableCopyOfWhatHappenedSinceLastClear];
}

但是在 ViewController 中，当我声明

-(IBAction)testPressed:(id)sender
{
CalculatorBrain *brain = self.brain;   
brain = [[CalculatorBrain alloc] init];
NSMutableArray *program = brain.whatHappenedSinceLastClear;
[brain runProgram:program];
}

在该行中，NSMutableArray *program = brain.whatHappenedSinceLastClear;我收到一条消息，上面写着“在'CalculatorBrain *'类型的对象上找不到属性'whatHappenedSinceLastClear'。

我究竟做错了什么？

Answer 1

试试这个：替换：

NSMutableArray *program = brain.whatHappenedSinceLastClear;

经过

NSMutableArray *program = [brain whatHappenedSinceLastClear];

在brain.h中

-(NSMutableArray *)whatHappenedSinceLastClear;

这应该有效。