如何存储来自NSUserDefaults的检索浮点数 [英] How to store an retrieve float from NSUserDefaults

问题描述

我在NSUserDefauts中存储和检索浮点数时遇到麻烦.我存储了该值，但是当我检索它时，它返回0.

I'm having trouble storing and retrieving a float in NSUserDefauts. I store the value, but when I retrieve it, it returns 0.

这是我尝试但没有奏效的东西:

here's what I tried and didn't work:

[pref setFloat:3.0f forKey:@"key"];
float value = [pref floatForKey:@"key"]; //value=0

[pref setFloat:3 forKey:@"key"];
float value = [pref floatForKey:@"key"];//value=0

[pref setObject:[NSNumber numberWithFloat:3] forKey:@"key"];
float value = [[pref objectForKey:@"key"]floatValue];//value=0

[pref setObject:[NSNumber numberWithFloat:3.0f] forKey:@"key"];
float value = [[pref objectForKey:@"key"]floatValue];//value=0

我在这里做错了什么?我已经尝试了这四段代码，但是当从NSUserDefaults检索浮点数时，它们都返回零.

What am I doing wrong here? I've tried these 4 pieces of code but they all return zero when retrieving the float from NSUserDefaults.

感谢您的帮助.谢谢！

推荐答案

您的代码中的第一个示例很好，假设此行:

The first example in your code is fine, assuming that this line:

NSUserDefaults *pref = [NSUserDefaults standardUserDefaults];

出现在它之前.正如我在评论中所建议的那样，您看到的行为表明 pref 为nil.

Appears before it. As I suggested in my comment, the behaviour you are seeing suggests that pref is nil.

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