在UIAlertView的输出中引用NSString？ [英] Referring to an NSString in output of UIAlertView?

问题描述

我有一个 NSString testString，它设置为我的应用程序中的一个值。然后，作为对按钮的响应，请在 UIAlertView 中按以下代码：

I have an NSString, testString which is set to a value in my app. Then as a response to a button press in UIAlertView I have the following code:

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {
    if (buttonIndex == 0) {
        NSLog(@"String: %@", testString);
    }
}

但是出于某些原因，这总是导致应用崩溃。我似乎无法弄清楚为什么。

But for sme reason, this always causes the app to crash. I can't seem to figure out why.

推荐答案

可能您使用一种便捷方法创建了字符串，但没有保留它，因此当涉及到警报的clickedButtonAtIndex时，它已经自动释放。
您应将其定义为

Probably you create your string with one of convenience methods and don't retain it, so when it comes to alert's clickedButtonAtIndex it's already autoreleased. You should define it as

@property (nonatomic, retain) NSString *testString;

在实施中：

@synthesize testString;

创建时：

self.testString = [NSString stringWithFormat:@"%@", @"My test string"];

和 [testString release]; 在dealloc上

然后，当在clickedButtonAtIndex中使用它时，可以确保您的testString具有正确的值

Then when you use it in clickedButtonAtIndex you can be sure your testString has a right value

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