Cocoa-Touch - 如何解析本地Json文件

Question

我是iOS开发新手,我正在尝试解析一个本地Json文件,如

{"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","rep4","1234","reponse","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样本,但是我收到了以下错误

-JSONValue失败.错误是:在对象键之后不期望令牌'值分隔符'.

Answer 1

JSON具有严格的键/值表示法,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,则不需要所有斜杠}
您的文件将是这样的:

{"quizz":[{"id":"1","Q1":"当米奇出生时","R1":"1920","R2":"1965","R3":"1923", "R4":"1234","响应":"1920"},{"id":"1","Q1":"开始冷战时","R1":"1920","R2": "1965年", "R3": "1923", "R4": "1234", "效应初探": "1920"}]}

我测试了这段代码:

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"]);
}

我得到的印象是,您复制了旧代码,因为您没有使用Apple的序列化和Enumerator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"]);
}

或者甚至是基于块的枚举的发烧友,如果需要快速安全的枚举,你还有一个索引.

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"]);
}];