[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, 50 insertions, 0 deletions

diff --git a/platform/darwin/test/MGLExpressionTests.mm b/platform/darwin/test/MGLExpressionTests.mm
index c91cf36d1a..e078c4f4b6 100644
--- a/platform/darwin/test/MGLExpressionTests.mm
+++ b/platform/darwin/test/MGLExpressionTests.mm
@@ -1006,4 +1006,54 @@ using namespace std::string_literals;
     }
 }
 
+- (void)testConvenienceInitializers {
+    {
+        NSExpression *expression = [NSExpression mgl_expressionForConditional:[NSPredicate predicateWithFormat:@"1 = 2"]
+                                                               trueExpression:MGLConstantExpression(@YES)
+                                                             falseExpresssion:MGLConstantExpression(@NO)];
+        
+        NSArray *jsonExpression = @[@"case", @[@"==", @1, @2], @YES, @NO];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @NO);
+    }
+    {
+        NSDictionary *stops = @{@0: MGLConstantExpression(@111), @1: MGLConstantExpression(@1111)};
+        NSExpression *expression = [NSExpression mgl_expressionForSteppingExpression:[NSExpression expressionForKeyPath:@"x"]
+                                                                      fromExpression:[NSExpression expressionForConstantValue:@11]
+                                                                               stops:[NSExpression expressionForConstantValue:stops]];
+        NSArray *jsonExpression = @[@"step", @[@"get", @"x"], @11, @0, @111, @1, @1111];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSDictionary *stops = @{@0: MGLConstantExpression(@100), @10: MGLConstantExpression(@200)};
+        NSExpression *expression = [NSExpression mgl_expressionForInterpolatingExpression:[NSExpression expressionForKeyPath:@"x"]
+                                                                            withCurveType:MGLExpressionInterpolationModeLinear
+                                                                               parameters:nil
+                                                                                    stops:[NSExpression expressionForConstantValue:stops]];
+        NSArray *jsonExpression = @[@"interpolate", @[@"linear"], @[@"get", @"x"], @0, @100, @10, @200];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSExpression *expression = [[NSExpression expressionForConstantValue:@"Old"] mgl_expressionByAppendingExpression:[NSExpression expressionForConstantValue:@"MacDonald"]];
+
+        NSArray *jsonExpression = @[@"concat", @"Old", @"MacDonald"];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([expression expressionValueWithObject:nil context:nil], @"OldMacDonald");
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+    {
+        NSDictionary *values = @{ MGLConstantExpression(@1): MGLConstantExpression(@"one") };
+        NSExpression *expression = [NSExpression mgl_expressionForMatchingExpression:[NSExpression expressionWithFormat:@"2 * 1"]
+                                                                        inDictionary:values
+                                                                   defaultExpression:[NSExpression expressionForConstantValue:@"default"]];
+        NSArray *jsonExpression =  @[@"match", @[@"*", @2, @1], @1, @"one", @"default"];
+        XCTAssertEqualObjects(expression.mgl_jsonExpressionObject, jsonExpression);
+        XCTAssertEqualObjects([NSExpression expressionWithMGLJSONObject:jsonExpression], expression);
+    }
+}
+
+
 @end