如何从方法正确返回NSMutableString [英] How to return correctly a NSMutableString from a method

问题描述

我正在寻找一种返回NSMutableString构造的字符串以避免泄漏的好方法:

I'm looking for a good way to return a string constructed by a NSMutableString avoiding leaking :

例如:

+(NSString *)myMethod{



 NSMutableString *numberToReturn = [[NSMutableString alloc] init];
 [numberToReturn appendString:@"lorem ipsum"];


 return numberToReturn;
}

泄漏仪器说我有这个变量泄漏.

The leak instrument said I had leak with this variable.

我尝试了自动发布，但是崩溃了 我试图返回一个副本或将可变字符串复制到nsstring中，但仍然存在泄漏.

I tried autorelease but it crashes I tried to return a copy or copying the mutablestring into a nsstring but leak still present.

有什么主意或把戏吗? 每次用户在文本字段中键入一个值时，我都有一个调用此方法的应用程序，因此由于内存管理不当而导致应用程序崩溃...

Any idea or trick? I'have a to call this method each time the user type a value into the textfield, so the application crashes due to bad memory management...

谢谢

推荐答案

您应使用-autorelease.您的方法应写为:

You should use -autorelease. Your method should be written as:

+ (NSString*)myMethod {
    NSMutableString *stringToReturn = [[NSMutableString alloc] init];
    [stringToReturn appendString:@"lorem ipsum"];

   return [stringToReturn autorelease];
}

如果发生崩溃，则故障在其他地方.

If there is a crash, the fault is elsewhere.

当然，您可以利用工厂方法来返回已经自动释放的实例，并将方法改写为

Of course, you can make use of factory methods that return an already-autoreleased instance, rewritting your method as

+ (NSString*)myMethod {
  NSMutableString *result = [NSMutableString string];
  [result appendString:@"lorem ipsum"];

  return result;
}

或者更好的例子，

+ (NSString*)myMethod {
    NSMutableString *result = [NSMutableString stringWithString:@"lorem ipsum"];
    //...do something with result;
    return result;
}

很明显，如果您的方法的唯一目的只是返回带有字符串的新字符串，则可以避免整个方法，如果确实需要可变的字符串，请使用[NSMutableString stringWithString:@"lorem ipsum"].

Obviously if you method's only purpose is just to return a new string with a string, you can avoid the whole method all together and use [NSMutableString stringWithString:@"lorem ipsum"] if you really need a mutable string.

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