[ios, macos] Add NSExpression convenience constructors and helper methods. (#11278)

* [ios, macos] Refactor convinience expression initializers.

# Conflicts:
#	platform/darwin/src/NSExpression+MGLAdditions.h
#	platform/darwin/src/NSExpression+MGLAdditions.mm
#	platform/ios/app/MBXViewController.m

* [ios, macos] Add MGL_MATCH convenience method.

# Conflicts:
#	platform/darwin/src/NSExpression+MGLAdditions.h
#	platform/darwin/src/NSExpression+MGLAdditions.mm
#	platform/darwin/test/MGLExpressionTests.mm

* [ios, macos] Add Swift friendly convenience methods name syntax..

# Conflicts:
#	platform/darwin/src/NSExpression+MGLAdditions.h

* [ios, macos] Update runtime styling examples.

# Conflicts:
#	platform/ios/app/MBXViewController.m

* [ios, macos] Add NSExpression variable expressions properties.

* [ios, macos] Clarify convenience initializer names.

* [ios, macos] Update Style Authors guides.

* [ios, macos] Fix cherry-pick merge.

* [ios, macos] Update convenience initializers documentation.

1 files changed, 16 insertions, 8 deletions

diff --git a/platform/ios/app/MBXViewController.m b/platform/ios/app/MBXViewController.m
index 0a76f8c0c5..391af5ea05 100644
--- a/platform/ios/app/MBXViewController.m
+++ b/platform/ios/app/MBXViewController.m
@@ -967,18 +967,20 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
                                       @10.0f: [UIColor redColor],
                                       @12.0f: [UIColor greenColor],
                                       @14.0f: [UIColor blueColor]};
-    waterLayer.fillColor = [NSExpression expressionWithFormat:
-                            @"mgl_interpolate:withCurveType:parameters:stops:($zoomLevel, 'linear', nil, %@)",
-                            waterColorStops];
+    NSExpression *fillColorExpression = [NSExpression mgl_expressionForInterpolatingExpression:NSExpression.zoomLevelVariableExpression
+                                                                                 withCurveType:MGLExpressionInterpolationModeLinear
+                                                                                    parameters:nil
+                                                                                         stops:[NSExpression expressionForConstantValue:waterColorStops]];
+    waterLayer.fillColor = fillColorExpression;
 
     NSDictionary *fillAntialiasedStops = @{@11: @YES,
                                            @12: @NO,
                                            @13: @YES,
                                            @14: @NO,
                                            @15: @YES};
-    waterLayer.fillAntialiased = [NSExpression expressionWithFormat:
-                                  @"mgl_step:from:stops:($zoomLevel, false, %@)",
-                                  fillAntialiasedStops];
+    waterLayer.fillAntialiased = [NSExpression mgl_expressionForSteppingExpression:NSExpression.zoomLevelVariableExpression
+                                                                    fromExpression:[NSExpression expressionForConstantValue:@NO]
+                                                                             stops:[NSExpression expressionForConstantValue:fillAntialiasedStops]];
 }
 
 - (void)styleRoadLayer
@@ -1467,10 +1469,16 @@ typedef NS_ENUM(NSInteger, MBXSettingsMiscellaneousRows) {
 
     // source, categorical function that sets any feature with a "fill" attribute value of true to red color and anything without to green
     MGLFillStyleLayer *fillStyleLayer = [[MGLFillStyleLayer alloc] initWithIdentifier:@"fill-layer" source:shapeSource];
-    fillStyleLayer.fillColor = [NSExpression expressionWithFormat:@"TERNARY(fill == YES, %@, %@)", [UIColor greenColor], [UIColor redColor]];
+    fillStyleLayer.fillColor = [NSExpression mgl_expressionForConditional:[NSPredicate predicateWithFormat:@"fill == YES"]
+                                                           trueExpression:[NSExpression expressionForConstantValue:[UIColor greenColor]]
+                                                         falseExpresssion:[NSExpression expressionForConstantValue:[UIColor redColor]]];
+                                                               
+    
 
     // source, identity function that sets any feature with an "opacity" attribute to use that value and anything without to 1.0
-    fillStyleLayer.fillOpacity = [NSExpression expressionWithFormat:@"TERNARY(opacity != nil, opacity, 1.0)"];
+    fillStyleLayer.fillOpacity = [NSExpression mgl_expressionForConditional:[NSPredicate predicateWithFormat:@"opacity != nil"]
+                                                             trueExpression:[NSExpression expressionForKeyPath:@"opacity"] 
+                                                           falseExpresssion:[NSExpression expressionForConstantValue:@1.0]];
     [self.mapView.style addLayer:fillStyleLayer];
 }