diff options
Diffstat (limited to 'platform/darwin/src/MGLVectorStyleLayer.h')
| -rw-r--r-- | platform/darwin/src/MGLVectorStyleLayer.h | 30 |
1 files changed, 24 insertions, 6 deletions
diff --git a/platform/darwin/src/MGLVectorStyleLayer.h b/platform/darwin/src/MGLVectorStyleLayer.h index f59ef4bf7f..ca09c11716 100644 --- a/platform/darwin/src/MGLVectorStyleLayer.h +++ b/platform/darwin/src/MGLVectorStyleLayer.h @@ -61,11 +61,15 @@ MGL_EXPORT <li><code>NSContainsPredicateOperatorType</code> (<code>CONTAINS</code>)</li> </ul> - To test whether a feature has or lacks a specific attribute, compare the attribute to `NULL` or `NIL`. Predicates created using the `+[NSPredicate predicateWithValue:]` method are also supported. String operators and custom operators are not supported. + To test whether a feature has or lacks a specific attribute, compare the + attribute to `NULL` or `NIL`. Predicates created using the + `+[NSPredicate predicateWithValue:]` method are also supported. String + operators and custom operators are not supported. For details about the predicate format string syntax, consult the “Predicate - Format String Syntax” chapter of the “Predicate Programming Guide” in Apple - developer documentation. + Format String Syntax” chapter of the + “<a href="https://developer.apple.com/library/content/documentation/Cocoa/Conceptual/Predicates/">Predicate Programming Guide</a>” + in Apple developer documentation. The predicate's left-hand expression must be a string that identifies a feature attribute or, alternatively, one of the following special attributes: @@ -121,15 +125,29 @@ MGL_EXPORT Automatic type casting is not performed. Therefore, a feature only matches this predicate if its value for the attribute in question is of the same type as the - value specified in the predicate. Also, operator modifiers `c`, `d`, and the - combined `cd` for case and diacritic insensitivity are unsupported for - comparison and aggregate operators that are used in the predicate. + value specified in the predicate. Also, operator modifiers such as `c` (for + case insensitivity), `d` (for diacritic insensitivity), and `l` (for locale + sensitivity) are unsupported for comparison and aggregate operators that are + used in the predicate. It is possible to create expressions that contain special characters in the predicate format syntax. This includes the `$` in the `$id` and `$type` special style attributes and also `hyphen-minus` and `tag:subtag`. However, you must use `%K` in the format string to represent these variables: `@"%K == 'LineString'", @"$type"`. + + ### Example + + To filter the layer to include only the features whose `index` attribute is 5 + or 10 and whose `ele` attribute is at least 1,500, you could create an + `NSCompoundPredicate` along these lines: + + ```swift + let layer = MGLLineStyleLayer(identifier: "contour", source: terrain) + layer.sourceLayerIdentifier = "contours" + layer.predicate = NSPredicate(format: "(index == 5 || index == 10) && ele >= 1500.0") + mapView.style?.addLayer(layer) + ``` */ @property (nonatomic, nullable) NSPredicate *predicate; |