类中声明一个变量如下：@property (nonatomic, copy) NSMutableArray *muArray; 以下初始化正确的方式是？
self.muArray = [[NSMutableArray alloc] init];
_muArray = [NSMutableArray new];
_muArray = [[NSMutableArray alloc] initWithCapacity:0];
self.muArray = [[NSMutableArray alloc] initWithObjects:@"0",nil];
