为iOS动态设置地图Pin颜色

我解析一个包含字符串0、1和2的xml

//供参考 0=绿色 1=红色 2=紫色

我有一个类可以确认mkannotation，它包含以下属性变量

CLLocationCoordinate2D  coordinate;
NSString            *title;
NSString            *subtitle;
MKPinAnnotationColor pinColor;

这个类名为MyAnnotation

现在在map视图的viewDidLoad中，我运行一个for循环来迭代解析的数据 如下图所示（locationArray保存了这些数据，我很好地提取了所有信息

 for (int i = 0; i < locationArray.count; i++) {
    myAnnotation =[[MyAnnotation alloc] init];

    NSString *thePointName = [[locationArray objectAtIndex:i]xmlName];
    NSString *theAddress = [[locationArray objectAtIndex:i]xmlAddress];

    NSString *latString = [[locationArray objectAtIndex:i]xmlLat];
    NSString *lonString = [[locationArray objectAtIndex:i]xmlLon];

现在在MKAnnotationView视图中，我执行以下操作

  - (MKAnnotationView *)mapView:(MKMapView *)mapView viewForAnnotation:(id     <MKAnnotation>)annotation

 {

// if it's the user location, just return nil.
    if ([annotation isKindOfClass:[MKUserLocation class]])
    return nil;

// try to dequeue an existing pin view first
static NSString* AnnotationIdentifier = @"AnnotationIdentifier";
MKPinAnnotationView* pinView = [[MKPinAnnotationView alloc]
                                  initWithAnnotation:annotation reuseIdentifier:AnnotationIdentifier];
pinView.animatesDrop=YES;
pinView.canShowCallout=YES;

    //set pin color to the correct colour
    if (myAnnotation.pinColor = MKPinAnnotationColorGreen) {
    pinView.pinColor = MKPinAnnotationColorGreen;
    }

    else if (myAnnotation.pinColor = MKPinAnnotationColorRed) {
    pinView.pinColor = MKPinAnnotationColorRed;

     }

    else if (myAnnotation.pinColor = MKPinAnnotationColorPurple){
    pinView.pinColor = MKPinAnnotationColorPurple;
    }



    UIButton* rightButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];
[rightButton setTitle:annotation.title forState:UIControlStateNormal];
[rightButton addTarget:self
                action:@selector(showDetails:)
      forControlEvents:UIControlEventTouchUpInside];
pinView.rightCalloutAccessoryView = rightButton;


    UIImageView *profileIconView = [[UIImageView alloc] initWithImage:[UIImage  imageNamed:@"Profile.png"]];
pinView.leftCalloutAccessoryView = profileIconView;

return pinView;
  }

---

注释视图中的此代码：

if (myAnnotation.pinColor = MKPinAnnotationColorGreen) {

不起作用的原因有两个：

它使用的是一个等号，用于赋值，而不是用于检查相等。它需要使用两个等号来检查相等。但是，这并不能解决主要问题，即原因#2

代码正在检查

myAnnotation

的值，该值是在此委托方法之外设置的变量。不能保证委托方法将与设置了

myAnnotation

的for循环同步调用。不要假设在调用

add之后会立即调用
viewForAnnotation
注释

。如果地图视图需要在缩放或平移后再次显示注释，则对于同一注释，甚至可以多次调用委托方法

相反，您必须使用传递给委托方法的

annotation

参数。这是对映射视图希望在委托方法的当前调用中查看的注释的引用

由于

注释

参数的类型一般为

id

，因此首先必须将其强制转换为自定义类，然后才能访问任何自定义属性：

//first make sure this annotation is our custom class before casting it...
if ([annotation isKindOfClass:[MyAnnotation class]])
{
    MyAnnotation *currentAnn = (MyAnnotation *)annotation;

    if (currentAnn.pinColor == MKPinAnnotationColorGreen) {
        pinView.pinColor = MKPinAnnotationColorGreen;
    }

    else if (currentAnn.pinColor == MKPinAnnotationColorRed) {
        pinView.pinColor = MKPinAnnotationColorRed;

    }

    else if (currentAnn.pinColor == MKPinAnnotationColorPurple) {
        pinView.pinColor = MKPinAnnotationColorPurple;
    }
}

或者更简单：

//first make sure this annotation is our custom class before casting it...
if ([annotation isKindOfClass:[MyAnnotation class]])
{
    MyAnnotation *currentAnn = (MyAnnotation *)annotation;        
    pinView.pinColor = currentAnn.pinColor;
}

（不相关，但是为什么代码设置了

rightButton

的标题，即使它不可见？

首先我是一个笨蛋：-）是的，我应该使用==已经很晚了，其次我真的很愚蠢，如果（[annotation isKindOfClass:[MyAnnotation class]]）{MyAnnotation*currentAnn=（MyAnnotation*）很多深夜都能赶上我，非常感谢你抽出时间！

//first make sure this annotation is our custom class before casting it...
if ([annotation isKindOfClass:[MyAnnotation class]])
{
    MyAnnotation *currentAnn = (MyAnnotation *)annotation;

    if (currentAnn.pinColor == MKPinAnnotationColorGreen) {
        pinView.pinColor = MKPinAnnotationColorGreen;
    }

    else if (currentAnn.pinColor == MKPinAnnotationColorRed) {
        pinView.pinColor = MKPinAnnotationColorRed;

    }

    else if (currentAnn.pinColor == MKPinAnnotationColorPurple) {
        pinView.pinColor = MKPinAnnotationColorPurple;
    }
}

//first make sure this annotation is our custom class before casting it...
if ([annotation isKindOfClass:[MyAnnotation class]])
{
    MyAnnotation *currentAnn = (MyAnnotation *)annotation;        
    pinView.pinColor = currentAnn.pinColor;
}