Question

以下是简单的代码：

// let's assume that I have to allocate this variable with alloc/init
NSString *someString = [[NSString alloc] initWithFormat:"%@", @"someString"];

NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
  [someClass someFunction: someString];
}];

[queue addOperation:op]

[someString release];

自从someString发布以来运行nsblockoperation时，此代码将崩溃。防止这种情况的最佳做法是什么？

谢谢。

编辑：ARC不是一个选择，因为它不是我的决定。有什么方法可以在MRC中解决这个问题吗？

EDIT2：以下代码怎么样？它会起作用吗？

// let's assume that I have to allocate this variable with alloc/init
NSString *someString = [[NSString alloc] initWithFormat:"%@", @"someString"];

[someString retain]
NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
  [someClass someFunction: someString];
  [someString release]
}];

[queue addOperation:op]

[someString release];

Answer 1

// let's say the variable is allocated with alloc/init
NSString *someString = [[[NSString alloc] initWithFormat:"%@", @"someString"] autorelease];

NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
  [someClass someFunction: someString];
}];

[queue addOperation:op];

周围有数十万个应用程序需要维护，不要使用ARC。将字符串包裹在自动释放中。我认为这应该有用，但我没有测试。

Answer 2

您确实应该使用自动引用计数，并将代码简化为

// let's say the variable is allocated with alloc/init
NSString *someString = @"someString";

NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
  [someClass someFunction: someString];
}];

[queue addOperation:op]

如果您真的必须使用手动参考计数，您可以这样做：

// let's assume that I have to allocate this variable with alloc/init
NSString *someString = [[NSString alloc] initWithFormat:"%@", @"someString"];

NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
  [someClass someFunction: someString];
  [someString release]
}];

[queue addOperation:op]

我知道它只是示例代码，但如果不是，你也可以这样做......;）

NSBlockOperation *op = [NSBlockOperation blockOperationWithBlock:^{
  [someClass someFunction:@"someString"];
}];

[queue addOperation:op]

NSBlockOperation和块中的对象

2 个答案: