Question

我有一个应用程序包含一个针指向世界上任何地方的特定位置的针，但当我使用下面的代码时，它可以工作，但针既旋转又移动，所以如何阻止它移动旋转的时候？

CLLocationCoordinate2D  currentLocation;
CLLocationDirection     currentHeading;
CLLocationDirection     cityHeading;
#define toRad(X) (X*M_PI/180.0)
#define toDeg(X) (X*180.0/M_PI)
#define FONT_SIZE 14.0f
#define CELL_CONTENT_WIDTH 320.0f
#define CELL_CONTENT_MARGIN 10.0f

- (void)viewDidLoad
{
    [super viewDidLoad];
    currentHeading=0.0;




    //  isArabic=[starter isArabic];


    locationManager = [[CLLocationManager alloc] init];
    locationManager.delegate = self;
    locationManager.distanceFilter = kCLDistanceFilterNone;
    locationManager.desiredAccuracy = kCLLocationAccuracyBest;



    if([CLLocationManager locationServicesEnabled]){
        [locationManager startUpdatingLocation];
    }
    [locationManager startUpdatingHeading];
}
- (void)locationManager:(CLLocationManager *)manager didUpdateToLocation:(CLLocation *)newLocation fromLocation:(CLLocation *)oldLocation {

    currentLocation = newLocation.coordinate;

    [self updateHeadingDisplays];
}
- (void)locationManager:(CLLocationManager *)manager
       didUpdateHeading:(CLHeading *)newHeading{


    float oldRad =  -manager.heading.trueHeading * M_PI / 180.0f;
    float newRad =  -newHeading.trueHeading * M_PI / 180.0f;
    CABasicAnimation *theAnimation;
    theAnimation=[CABasicAnimation animationWithKeyPath:@"transform.rotation"];
    theAnimation.fromValue = [NSNumber numberWithFloat:oldRad];
    theAnimation.toValue=[NSNumber numberWithFloat:newRad];
    theAnimation.duration = 0.5f;
    [compass.layer addAnimation:theAnimation forKey:@"animateMyRotation"];
    compass.transform = CGAffineTransformMakeRotation(newRad);

    NSLog(@"%f (%f) => %f (%f)", manager.heading.trueHeading, oldRad, newHeading.trueHeading, newRad);
    // if (newHeading.headingAccuracy < 0)
    //    return;

    // Use the true heading if it is valid.
    CLLocationDirection  theHeading = ((newHeading.trueHeading > 0) ?
                                       newHeading.trueHeading : newHeading.magneticHeading);


    cityHeading = [self directionFrom:currentLocation ];


    currentHeading = theHeading;

    [self updateHeadingDisplays];



}
- (void)updateHeadingDisplays {
    // Animate Compass


    [UIView     animateWithDuration:0.6
                              delay:0.0
                            options:UIViewAnimationOptionBeginFromCurrentState | UIViewAnimationOptionCurveEaseOut | UIViewAnimationOptionAllowUserInteraction
                         animations:^{
                             CGAffineTransform headingRotation = CGAffineTransformRotate(CGAffineTransformMakeTranslation(0, 0), (CGFloat)toRad(cityHeading)-toRad(currentHeading));

                             needle.transform = headingRotation;
                         }
                         completion:^(BOOL finished) {

                         }];



}

-(CLLocationDirection) directionFrom: (CLLocationCoordinate2D) startPt  {

    double lat1 = toRad(startPt.latitude);
    double lat2 = toRad(21.4266700 );
    double lon1 = toRad(startPt.longitude);
    double lon2 = toRad(39.8261100);
    double dLon = (lon2-lon1);

    double y = sin(dLon) * cos(lat2);
    double x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon);
    double brng = toDeg(atan2(y, x));

    brng = (brng+360);
    brng = (brng>360)? (brng-360) : brng;

    return brng;

}

Answer 1

在评论的屏幕截图中，您似乎正在使用自动布局（如您所见）。但随着自动布局出现一定的行为。您可以在大小检查器中看到来自界面构建器的警告：

所选视图没有约束。在构建时，将为视图生成显式左，顶，宽度和高度约束。

谁知道默认情况下对视图应用了哪些约束！如果将图像视图的中心限制在特定位置，则指南针图像应围绕其中心旋转。

例如，您可以控制从图像视图拖动到父级，并在“容器中”选择“垂直”和“水平”方向。

使用CGAffineTransform只旋转而不移动？

1 个答案: