Adds JSONHelper methods to read strings. (+1 squashed commit)

Squashed commits:
[30b0a71] Adds JSONHelper methods to read strings.

iOS/MonsterCards/Helpers/JSONHelper.h

@@ -0,0 +1,21 @@
+//
+//  JSONHelper.h
+//  MonsterCards
+//
+//  Created by Tom Hicks on 9/15/20.
+//  Copyright © 2020 Tom Hicks. All rights reserved.
+//
+
+#import <Foundation/Foundation.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface JSONHelper : NSObject
+
++(NSString*)readStringFromDictionary:(NSDictionary*)dictionary forKey:(NSString*)key;
++(NSString*)readStringFromDictionary:(NSDictionary*)dictionary forKey:(NSString*)key withDefaultValue:(NSString* _Nullable)defaultValue;
++(NSString*)readStringFromArray:(NSArray*)array forIndex:(NSUInteger)index;
++(NSString*)readStringFromArray:(NSArray*)array forIndex:(NSUInteger)index withDefaultValue:(NSString* _Nullable)defaultValue;
+@end
+
+NS_ASSUME_NONNULL_END

iOS/MonsterCards/Helpers/JSONHelper.m

@@ -0,0 +1,39 @@
+//
+//  JSONHelper.m
+//  MonsterCards
+//
+//  Created by Tom Hicks on 9/15/20.
+//  Copyright © 2020 Tom Hicks. All rights reserved.
+//
+
+#import "JSONHelper.h"
+
+@implementation JSONHelper
+
+NSString* coerceObjectToString(NSObject *object, NSString *defaultValue) {
+    if ([object isKindOfClass:[NSString class]]) {
+        return (NSString*)object;
+    }
+
+    return defaultValue;
+}
+
++(NSString*)readStringFromDictionary:(NSDictionary*)dictionary forKey:(NSString*)key {
+    return [JSONHelper readStringFromDictionary:dictionary forKey:key withDefaultValue:nil];
+}
+
++(NSString*)readStringFromDictionary:(NSDictionary*)dictionary forKey:(NSString*)key withDefaultValue:(NSString* _Nullable)defaultValue {
+    NSObject *object = [dictionary objectForKey:key];
+    return coerceObjectToString(object, defaultValue);
+}
+
++(NSString*)readStringFromArray:(NSArray*)array forIndex:(NSUInteger)index{
+    return [JSONHelper readStringFromArray:array forIndex:index withDefaultValue:nil];
+}
+
++(NSString*)readStringFromArray:(NSArray*)array forIndex:(NSUInteger)index withDefaultValue:(NSString* _Nullable)defaultValue {
+    NSObject *object = [array objectAtIndex:index];
+    return coerceObjectToString(object, defaultValue);
+}
+
+@end