Mapbox 表達式檢查 MGLStyleLayer 的屬性並與字符串進行比較

Question

In the mapView:didFinishLoadingStyle: method, I would like to be able to check to see if a MGLSymbolStyleLayer uses a specific class , similar to how we can use filter in a JSON style file to apply a style to only a certain class:

但是，就我而言，我想檢查並查看 map 上是否存在 class，如果它是字符串數組的一部分，則將其隱藏：

NSArray *poiTypesExcluded = @[@"airport"];
for (NSString *poiType in poiTypesExcluded) {
        
    layer.visible = [NSExpression expressionWithFormat:@"class != %@", poiType];
        
}

這給了我錯誤：

Unable to parse the format string "class != %@ == 1" 。

關於如何編寫NSExpression以便能夠將class屬性與另一個字符串進行比較的任何幫助？

Answer 1

我在這上面浪費了很多時間，最后它比我想象的要容易：

NSArray *poiTypesExcluded = @[@"airport", @"grocery", @"bank"];
NSMutableArray *predicates = [[NSMutableArray alloc] init];
for (NSString *poiType in poiTypesExcluded) {
    
    [predicates addObject:[NSPredicate predicateWithFormat:@"class != %@", poiType]];
    
}

symbolLayer.predicate = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];