[ios, macos] added a distance formatter

3 files changed, 91 insertions, 0 deletions

diff --git a/platform/darwin/src/MGLDistanceFormatter.h b/platform/darwin/src/MGLDistanceFormatter.h
new file mode 100644
index 0000000000..46aad9a940
--- /dev/null
+++ b/platform/darwin/src/MGLDistanceFormatter.h
@@ -0,0 +1,26 @@
+#import <Foundation/Foundation.h>
+#import <CoreLocation/CoreLocation.h>
+
+#import "MGLFoundation.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ `MGLDistanceFormatter` implements a formatter object meant to be used for
+ geographic distances. The user’s current locale will be used by default
+ but it can be overriden by changing the locale property of the numberFormatter.
+ */
+MGL_EXPORT
+@interface MGLDistanceFormatter : NSLengthFormatter
+
+/**
+ Returns a localized formatted string for the provided distance.
+ 
+ @param distance The distance, measured in meters.
+ @return A localized formatted distance string including units.
+ */
+- (NSString *)stringFromDistance:(CLLocationDistance)distance;
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/platform/darwin/src/MGLDistanceFormatter.m b/platform/darwin/src/MGLDistanceFormatter.m
new file mode 100644
index 0000000000..e77e48b512
--- /dev/null
+++ b/platform/darwin/src/MGLDistanceFormatter.m
@@ -0,0 +1,35 @@
+#import "MGLDistanceFormatter.h"
+
+@interface MGLDistanceFormatter()
+@end
+
+@implementation MGLDistanceFormatter
+
+static const CLLocationDistance METERS_PER_MILE = 1609.344;
+static const double YARDS_PER_MILE = 1760.0;
+static const double FEET_PER_MILE = YARDS_PER_MILE * 3.0;
+
+- (NSString *)stringFromDistance:(CLLocationDistance)distance {
+    double miles = distance / METERS_PER_MILE;
+    double feet = miles * FEET_PER_MILE;
+    
+    NSLengthFormatterUnit unit = NSLengthFormatterUnitMillimeter;
+    [self unitStringFromMeters:distance usedUnit:&unit];
+    
+    self.numberFormatter.roundingIncrement = @0.25;
+    
+    if (unit == NSLengthFormatterUnitYard) {
+        if (miles > 0.2) {
+            unit = NSLengthFormatterUnitMile;
+            return [self stringFromValue:miles unit:unit];
+        } else {
+            unit = NSLengthFormatterUnitFoot;
+            self.numberFormatter.roundingIncrement = @50;
+            return [self stringFromValue:feet unit:unit];
+        }
+    } else {
+        return [self stringFromMeters:distance];
+    }
+}
+
+@end
diff --git a/platform/darwin/test/MGLDistanceFormatterTests.m b/platform/darwin/test/MGLDistanceFormatterTests.m
new file mode 100644
index 0000000000..f15ad9d313
--- /dev/null
+++ b/platform/darwin/test/MGLDistanceFormatterTests.m
@@ -0,0 +1,30 @@
+#import <Mapbox/Mapbox.h>
+#import <XCTest/XCTest.h>
+
+@interface MGLDistanceFormatterTests : XCTestCase
+
+@end
+
+@implementation MGLDistanceFormatterTests
+
+- (void)testAbbreviatedMetricUnits {
+    MGLDistanceFormatter *formatter = [[MGLDistanceFormatter alloc] init];
+    formatter.numberFormatter.locale = [NSLocale localeWithLocaleIdentifier:@"en_CA"];
+    for (CLLocationDistance distance=0; distance <= 10000; distance+=5) {
+        NSString *unit = [[formatter stringFromDistance:distance] componentsSeparatedByString:@" "][1];
+        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF IN %@", @[@"mm", @"cm", @"m", @"km"]];
+        XCTAssert([predicate evaluateWithObject:unit], @"Should only contain metric units");
+    }
+}
+
+- (void)testAbbreviatedImperialUnits {
+    MGLDistanceFormatter *formatter = [[MGLDistanceFormatter alloc] init];
+    formatter.numberFormatter.locale = [NSLocale localeWithLocaleIdentifier:@"en_US"];
+    for (CLLocationDistance distance=0; distance <= 10000; distance+=5) {
+        NSString *unit = [[formatter stringFromDistance:distance] componentsSeparatedByString:@" "][1];
+        NSPredicate *predicate = [NSPredicate predicateWithFormat:@"SELF IN %@", @[@"ft", @"mi"]];
+        XCTAssert([predicate evaluateWithObject:unit], @"Should only contain imperial units");
+    }
+}
+
+@end