objective-c - Cocoa-Touch - 如何解析本地 Json 文件

Question

我是 iOS 开发新手，我正在尝试解析本地 Json 文件，例如

{"quizz":[{"id":"1","Q1":"米奇什么时候出生","R1":"1920","R2":"1965","R3 ":"1923","R4","1234","re​​sponse","1920"},{"id":"1","Q1":"什么时候开始冷战","R1":"1920 ","R2":"1965","R3":"1923","re​​p4","1234","响应","1920"}]}

这是我的代码:

 NSString *filePath = [[NSBundle mainBundle] pathForResource:@"data" ofType:@"json"];
NSString *myJSON = [[NSString alloc] initWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:NULL];
// Parse the string into JSON
NSDictionary *json = [myJSON JSONValue];

// Get all object
NSArray *items = [json valueForKeyPath:@"quizz"];

NSEnumerator *enumerator = [items objectEnumerator];
NSDictionary* item;
while (item = (NSDictionary*)[enumerator nextObject]) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}

我在这个网站上找到了一个示例，但我收到以下错误

-JSONValue 失败。错误是:对象键后不应有 token “值分隔符”。

Answer 1

JSON 具有严格的键/值表示法，您的 R4 和响应的键/值对不正确。试试这个:

NSString *jsonString = @"{\"quizz\":[{\"id\":\"1\",\"Q1\":\"When Mickey was born\",\"R1\":\"1920\",\"R2\":\"1965\",\"R3\":\"1923\",\"R4\":\"1234\",\"response\":\"1920\"}]}";

^{如果您从文件中读取字符串，则不需要所有斜线}
您的文件将是这样的:

{"quizz":[{"id":"1","Q1":"When Mickey was born","R1":"1920","R2":"1965","R3":"1923","R4":"1234","response":"1920"},{"id":"1","Q1":"When start the cold war","R1":"1920","R2":"1965","R3":"1923","R4":"1234","reponse":"1920"}]}

---

我用这段代码测试过:

NSString *jsonString = @"{\"quizz\":[{\"id\":\"1\",\"Q1\":\"When Mickey was born\",\"R1\":\"1920\",\"R2\":\"1965\",\"R3\":\"1923\",\"R4\":\"1234\",\"response\":\"1920\"}, {\"id\":\"1\",\"Q1\":\"When start the cold war\",\"R1\":\"1920\",\"R2\":\"1965\",\"R3\":\"1923\",\"R4\":\"1234\",\"reponse\":\"1920\"}]}";
NSLog(@"%@", jsonString);
NSError *error =  nil;
NSDictionary *json = [NSJSONSerialization JSONObjectWithData:[jsonString dataUsingEncoding:NSUTF8StringEncoding] options:kNilOptions error:&error];

NSArray *items = [json valueForKeyPath:@"quizz"];

NSEnumerator *enumerator = [items objectEnumerator];
NSDictionary* item;
while (item = (NSDictionary*)[enumerator nextObject]) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}

我的印象是你复制了旧代码，因为你没有使用苹果的序列化和枚举器而不是 Fast Enumeration .整个枚举的东西可以简单地写成

NSArray *items = [json valueForKeyPath:@"quizz"];
for (NSDictionary *item in items) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}

甚至更喜欢 block based enumeration ，如果需要快速和安全的枚举，您是否有额外的索引。

NSArray *items = [json valueForKeyPath:@"quizz"];
[items enumerateObjectsUsingBlock:^(NSDictionary *item , NSUInteger idx, BOOL *stop) {
    NSLog(@"clientId = %@",  [item objectForKey:@"id"]);
    NSLog(@"clientName = %@",[item objectForKey:@"Q1"]);
    NSLog(@"job = %@",       [item objectForKey:@"Q2"]);
}];