Fixed secure coding issue that classes object couldn't be decoded. (#830)

Co-authored-by: Vein Guo <vein.guo@ui.com>
Co-authored-by: Frank <472730949@qq.com>

Author: VeinGuo

MJExtension/NSObject+MJCoding.m

@@ -44,7 +44,11 @@ - (void)mj_decode:(NSCoder *)decoder
         if ([ignoredCodingPropertyNames containsObject:property.name]) return;
 
         // fixed `-[NSKeyedUnarchiver validateAllowedClass:forKey:] allowed unarchiving safe plist type ''NSNumber'(This will be disallowed in the future.)` warning.
-        id value = [decoder decodeObjectOfClasses:[NSSet setWithObjects:NSNumber.class, property.type.typeClass, nil] forKey:property.name];
+        Class genericClass = [property objectClassInArrayForClass:property.srcClass];
+        // If genericClass exists, property.type.typeClass would be a collection type(Array, Set, Dictionary). This scenario([obj, nil, obj, nil]) would not happened.
+        NSSet *classes = [NSSet setWithObjects:NSNumber.class,
+                          property.type.typeClass, genericClass, nil];
+        id value = [decoder decodeObjectOfClasses:classes forKey:property.name];
         if (value == nil) { // 兼容以前的MJExtension版本
             value = [decoder decodeObjectForKey:[@"_" stringByAppendingString:property.name]];
         }

MJExtensionTests/MJExtensionTests.m

@@ -20,6 +20,7 @@
 #import "MJFrenchUser.h"
 #import "MJCat.h"
 #import <MJExtensionTests-Swift.h>
+#import "MJPerson.h"
 
 @interface MJExtensionTests : XCTestCase
 
@@ -458,6 +459,42 @@ - (void)testCoding {
     MJExtensionLog(@"name=%@, price=%f", decodedBag.name, decodedBag.price);
 }
 
+- (void)testCodingModelArrayProperty {
+    // 有 NSArray 属性 模型
+    MJPerson *person = [[MJPerson alloc] init];
+    person.name = @"boy1";
+    person.isVIP = YES;
+    
+    MJPerson *friend1 = [[MJPerson alloc] init];
+    friend1.name = @"friend1";
+    friend1.isVIP = YES;
+    
+    MJPerson *friend2 = [[MJPerson alloc] init];
+    friend2.name = @"friend2";
+    friend2.isVIP = NO;
+
+    person.friends = @[friend1, friend2];
+    person.books = @[@"book1", @"book2"];
+    
+    NSString *file = [NSTemporaryDirectory() stringByAppendingPathComponent:@"person.data"];
+    NSError *error = nil;
+    // 归档
+    NSData *data = [NSKeyedArchiver archivedDataWithRootObject:person
+                                         requiringSecureCoding:YES
+                                                         error:&error];
+    BOOL write = [data writeToFile:file atomically:true];
+    XCTAssert(write);
+    
+    // 解档
+    NSData *readData = [NSFileManager.defaultManager contentsAtPath:file];
+    error = nil;
+    MJPerson *decodedPerson = [NSKeyedUnarchiver unarchivedObjectOfClass:MJPerson.class
+                                                                  fromData:readData
+                                                                     error:&error];
+    XCTAssert(decodedPerson.friends.count == 2);
+    XCTAssert(decodedPerson.books.count == 2);
+}
+
 #pragma mark  统一转换属性名（比如驼峰转下划线）
 - (void)testReplacedKeyFromPropertyName121 {
     // 1.定义一个字典

MJExtensionTests/Model/MJPerson.h

@@ -12,7 +12,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 @interface MJPerson : NSObject
 @property (copy, nonatomic) NSString *name;
+@property (nonatomic) BOOL isVIP;
 @property (strong, nonatomic) NSArray<MJPerson *> *friends;
+@property (strong, nonatomic) NSArray<NSString *> *books;
 @end
 
 NS_ASSUME_NONNULL_END

MJExtensionTests/Model/MJPerson.m

@@ -9,8 +9,12 @@
 #import "MJPerson.h"
 #import <MJExtension/MJExtension.h>
 
+// NSSecureCoding实现
+MJSecureCodingImplementation(MJPerson, YES)
+
 @implementation MJPerson
 + (NSDictionary *)mj_objectClassInArray {
-    return  @{@"friends" : @"MJPerson"};
+    return @{@"friends": [MJPerson class],
+             @"books": [NSString class]};
 }
 @end