没有得到 NSLibraryDirectory 的完整路径

Question

我想从位于NSLibraryDirectory 的文件夹中获取图像。

 NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory,NSUserDomainMask, YES);
 NSString *documentsDirectory = [[paths objectAtIndex:0] stringByAppendingPathComponent:[NSString stringWithFormat:str]];

 NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent: [@"images" stringByAppendingFormat:@"%d",[[NSUserDefaults standardUserDefaults] integerForKey:@"HighScore"]] stringByAppendingFormat:@".png"];
 img = [UIImage imageWithContentsOfFile:getImagePath];
 NSLog(@"img:%@", img);

这是我使用的代码

getImagePath 的打印说明：

/用户/管理员/库/应用程序支持/iPhone 模拟器/5.0/Applications/6842528E-9629-4DE7-96C1-A46AEB8A8EE0/Library/Thapa

应该是：

getImagePath 的打印说明：

/用户/管理员/库/应用程序支持/iPhone 模拟器/5.0/Applications/6842528E-9629-4DE7-96C1-A46AEB8A8EE0/Library/Thapa/images47.png

这个不知道怎么实现的，我试过的都在上面。

提前致谢

Answer 1

首先，您在一行代码中做了太多事情。编写代码的最佳做法是保持简单（这样您的代码对您和其他任何查看它的人都是可读的）。

当我看到这一行时：

NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent: [@"images" stringByAppendingFormat:@"%d",[[NSUserDefaults standardUserDefaults] integerForKey:@"HighScore"]] stringByAppendingFormat:@".png"];

那里发生的事情太多了！

为什么不这样做：

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory,     NSUserDomainMask, YES);
if(paths)
{
    NSString *documentsDirectory = [[paths objectAtIndex:0] stringByAppendingPathComponent:[NSString stringWithFormat:str]];
    if(documentsDirectory)
    {
        NSInteger highScoreNumber = [[NSUserDefault standardUserDefaults] integerForKey: @"HighScore"];
        NSString * numberGraphicFilename = [NSString stringWithFormat: @"images%d.png", highScoreNumber ];
        if(numberGraphicFilename)
        {
            NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent: numberGraphicFilename];
            if(getImagePath)
            {
                img = [UIImage imageWithContentsOfFile:getImagePath];
            }
        }
    }
}

奖励：这也为您的代码引入了错误检查/处理的概念。

要编写更多代码，但阅读和遵循要容易得多。走这条路，您也许可以找出问题所在。

Answer 2

把getImagePath改成

NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent: [@"YourSubFolderName/images" stringByAppendingFormat:@"%d",[[NSUserDefaults standardUserDefaults] integerForKey:@"HighScore"]] stringByAppendingFormat:@".png"];

所以您的代码如下所示

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSLibraryDirectory,     NSUserDomainMask, YES);
NSString *documentsDirectory= [paths objectAtIndex:0];

NSString *getImagePath = [documentsDirectory stringByAppendingPathComponent: [@"YourSubFolderName/images" stringByAppendingFormat:@"%d",[[NSUserDefaults standardUserDefaults] integerForKey:@"HighScore"]] stringByAppendingFormat:@".png"];
img = [UIImage imageWithContentsOfFile:getImagePath];
NSLog(@"img:%@", img);