objective-c - 无法将对象添加到 NSMutableArray

Question

所以我有以下代码：

NSMutableArray *array
array=[[NSMutableArray alloc] init];
[array addObject: object1];
[array addObject: object2];
NSLog(@"%@",array);

当我在连接到 Mac 的 iPod 中使用该应用程序时，NSLog 只写入 null，我没有得到 object1 object2。我究竟做错了什么？

PS：数组是.h中的一个属性@property (nonatomic, retain) NSMutableArray *array;

Answer 1

应该是：

array=[[NSMutableArray alloc] init];

Answer 2

您可以尝试在一行中完成。

 NSMutableArray *array = [[NSMutableArray alloc] arrayWithObjects:@"a", @"b", nil];
 NSLog(@"%@",array);

Answer 3

You declared array as a property. Its corresponding iVar gets initialized to nil. So in your init method you have to initialize it:

Assuming you used

@synthesize array;

In your init method

if (self) {
//other init stuff
array = [[NSMutableArray array] retain];
}

Then when adding stuff

[self.array addObject: object];

Also note that he objects you put in there have to be properly initialized and r not nil. So try to log this too

NSLog("the object %@ was put in array. Array contains: %@",object, self.array);

And in dealloc, release your array!

Answer 4

你[[NSMutableArray array] init]应该是[[NSMutableArray alloc] init]。这会起作用，但它不是初始化对象的正确方法。您没有发布您array的内容，我假设您声明它是错误的。它应该是一个指向NSMutableArray对象的指针。这是一个工作代码：

NSMutableArray *array=[[NSMutableArray alloc] init];
[array addObject: @"a"];
[array addObject: @"b"];
NSLog(@"%@",array);

Answer 5

你根本没有初始化你的数组，这就是它不返回任何东西的原因。

array=[[NSMutableArray alloc] init];
[array addObject: object1];
[array addObject: object2];
NSLog(@" Array is:%@",array);

记得之后释放它（除非你使用 ARC）