解析本地文件中的 JSON 内容
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Parse JSON contents in local file
提问by cs1.6
How can I parse my JSON file stored in the application?
如何解析存储在应用程序中的 JSON 文件？
These are in my JSON file contents:
这些在我的 JSON 文件内容中：
[{"number":"01001","lieu":"paris"}{"number":"01002","lieu":"Dresden"}]
I've tried the following code:
我试过以下代码：
NSString *filePath = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"json"];
//création d'un string avec le contenu du JSON
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];
//Parsage du JSON à l'aide du framework importé
NSDictionary *json = [myJSON JSONValue];
NSArray *statuses = [json objectForKey:@"number"];
for (NSDictionary *status in statuses)
{
NSLog(@"%@ ", [status objectForKey:@"lieu"]);
}
回答by
Firstly, note there's a comma missing between the two objects in your JSON string.
首先，请注意 JSON 字符串中的两个对象之间缺少逗号。
Secondly, note that your JSON string contains a top-level array. So, instead of:
其次，请注意您的 JSON 字符串包含一个顶级数组。所以，而不是：
NSDictionary *json = [myJSON JSONValue];
use:
用：
NSArray *statuses = [myJSON JSONValue];
Each element in the array is an object (a dictionary) with two name-value pairs (key-object pairs), one for numberand another one for lieu:
数组中的每个元素都是一个对象（字典），具有两个名称-值对（键-对象对），一个 fornumber和另一个 for lieu：
for (NSDictionary *status in statuses) {
NSString *number = [status objectForKey:@"number"];
NSString *lieu = [status objectForKey:@"lieu"];
…
}
You might also want to check whether the file could be read:
您可能还想检查文件是否可以被读取：
//Creating a string with the contents of JSON
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];
if (!myJSON) {
NSLog(@"File couldn't be read!");
return;
}
回答by Dirty Henry
Here is a suggested full implementation:
这是建议的完整实现：
NSString *jsonFilePath = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"json"];
if (!jsonFilePath) {
// ... do something ...
}
NSError *error = nil;
NSInputStream *inputStream = [[NSInputStream alloc] initWithFileAtPath:jsonFilePath];
[inputStream open];
id jsonObject = [NSJSONSerialization JSONObjectWithStream: inputStream
options:kNilOptions
error:&error];
[inputStream close];
if (error) {
// ... do something ...
}
