Question

我试图找到使用NSTimer函数定期插入数组的10个信号强度值的平均值。我知道计时器正在运行，因为控制台日志，但10个值的数组没有。代码中是否存在小错误，或者if / else语句可能存在问题？

- (IBAction)getSignalAvg:(id)sender {

    myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                               target:self
                                             selector:@selector(arrayBuild)
                                             userInfo:nil
                                              repeats:YES];

}

- (void)arrayBuild {

    loopCount++;

    // Initialise Array
    NSMutableArray *resultsArray = [[NSMutableArray alloc]init];

    if (loopCount >= 11) {

        // Invalidate Timer
        [myTimer invalidate];
        myTimer = nil;

        // Find Average
        NSNumber *avg = [resultsArray valueForKeyPath:@"@avg.self"];

        // Change Text of Label to Average & Log
        self.avgSignal.text = [NSString stringWithFormat:@"%@",avg];
        NSLog(@"%@",avg);



    }else{

        // Declare Signal Strength
        float signalstrength = CTGetSignalStrength();

        // Individual Result & Convert to Integer
        NSString *result = [NSString stringWithFormat:@"%f", signalstrength];
        NSInteger resultInt = [result integerValue];

        // Add Object
        [resultsArray addObject:[NSNumber numberWithFloat:resultInt]];

        // Change Text of Label Each Second
        self.avgSignal.text = [NSString stringWithFormat:@"%d",loopCount];
        NSLog(@"%f",signalstrength);

    }
}

Answer 1

每次调用arrayBuild方法时，您都会创建一个新的NSMutableArray，因此您只有一个值。

您需要为NSMutableArray resultsArray创建一个类实例。只需在此类的.h文件中声明一个属性，如：

@property (nonatomic, strong) NSMutableArray *resultsArray;

在班级的init中：

- (instancetype)init{
    self = [super init];

    if (self) {
        _resultsArray = [[NSMutableArray alloc]init];
    }

    return self;
}

然后移除NSMutableArray *resultsArray = [[NSMutableArray alloc]init];中的arrayBuild并使用self.resultsArray的{{1}}个身份。

Answer 2

在.h文件中声明你是resultArray，因为每次你创建新数组时都是n。这就是为什么你无法做到这一点的原因。所以请像这样使用

.h文件

NSMutableArray *resultsArray;

.m文件

- (IBAction)getSignalAvg:(id)sender {

    myTimer = [NSTimer scheduledTimerWithTimeInterval:1.0
                                               target:self
                                             selector:@selector(arrayBuild)
                                             userInfo:nil repeats:YES];
            // Initialise Array
  if([resultArray count] == 0)
    resultsArray = [[NSMutableArray alloc]init];                                  
  else
     [resultArray removeAllObjects];
}

- (void)arrayBuild {

    loopCount++;



    if (loopCount >= 11) {

        // Invalidate Timer
        [myTimer invalidate];
        myTimer = nil;

        // Find Average
        NSNumber *avg = [resultsArray valueForKeyPath:@"@avg.self"];

        // Change Text of Label to Average & Log
        self.avgSignal.text = [NSString stringWithFormat:@"%@",avg];
        NSLog(@"%@",avg);



    }else{

        // Declare Signal Strength
        float signalstrength = CTGetSignalStrength();

        // Individual Result & Convert to Integer
        NSString *result = [NSString stringWithFormat:@"%f", signalstrength];
        NSInteger resultInt = [result integerValue];

        // Add Object
        [resultsArray addObject:[NSNumber numberWithFloat:resultInt]];

        // Change Text of Label Each Second
        self.avgSignal.text = [NSString stringWithFormat:@"%d",loopCount];
        NSLog(@"%f",signalstrength);

    }
}

如何在Objective-C中找到数组中10个值的平均值

2 个答案: