add saveLeanBodyMass

RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.h

@@ -26,5 +26,6 @@
 - (void)body_saveBodyFatPercentage:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
 
 - (void)body_getLatestLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
+- (void)body_saveLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback;
 
 @end

RCTAppleHealthKit/RCTAppleHealthKit+Methods_Body.m

@@ -259,7 +259,6 @@
 
 - (void)body_saveBodyFatPercentage:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
 {
-    
     double percentage = [RCTAppleHealthKit doubleValueFromOptions:input];
     NSDate *sampleDate = [RCTAppleHealthKit dateFromOptionsDefaultNow:input];
     HKUnit *unit = [HKUnit percentUnit];
@@ -307,4 +306,25 @@
     }];
 }
 
+
+- (void)body_saveLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback
+{
+    double mass = [RCTAppleHealthKit doubleValueFromOptions:input];
+    NSDate *sampleDate = [RCTAppleHealthKit dateFromOptions:input key:@"startDate" withDefault:[NSDate date]];
+    HKUnit *unit = [RCTAppleHealthKit hkUnitFromOptions:input key:@"unit" withDefault:[HKUnit poundUnit]];
+    
+    HKQuantity *massQuantity = [HKQuantity quantityWithUnit:unit doubleValue:mass];
+    HKQuantityType *massType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierLeanBodyMass];
+    HKQuantitySample *massSample = [HKQuantitySample quantitySampleWithType:massType quantity:massQuantity startDate:sampleDate endDate:sampleDate];
+    
+    [self.healthStore saveObject:massSample withCompletion:^(BOOL success, NSError *error) {
+        if (!success) {
+            NSLog(@"error saving lean body mass sample: %@", error);
+            callback(@[RCTMakeError(@"error saving lean body mass sample", error, nil)]);
+            return;
+        }
+        callback(@[[NSNull null], @(mass)]);
+    }];
+}
+
 @end

RCTAppleHealthKit/RCTAppleHealthKit.m

@@ -109,6 +109,11 @@ RCT_EXPORT_METHOD(getLatestLeanBodyMass:(NSDictionary *)input callback:(RCTRespo
     [self body_getLatestLeanBodyMass:input callback:callback];
 }
 
+RCT_EXPORT_METHOD(saveLeanBodyMass:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
+{
+    [self body_saveLeanBodyMass:input callback:callback];
+}
+
 RCT_EXPORT_METHOD(getStepCount:(NSDictionary *)input callback:(RCTResponseSenderBlock)callback)
 {
     [self fitness_getStepCountOnDay:input callback:callback];

docs/saveLeanBodyMass().md

+save a numeric lean body mass value to Healthkit
+
+`saveLeanBodyMass` accepts an options object containing a numeric weight value:
+```javascript
+let options = {
+  value: 155.6 // lbs
+}
+```
+
+```javascript
+AppleHealthKit.saveLeanBodyMass(options: Object, (err: Object, results: Object) => {
+    if (err) {
+        console.log("error saving lean body mass to Healthkit: ", err);
+        return;
+    }
+    // Done
+});
+```