我正在编写一个代码来创建一个应用程序,其中一组问题及其选项和答案正由json解析获取。我在viewDidLoad方法中做了这一切。
这是到目前为止的代码。解析代码工作正常。
- (void)viewDidLoad {
[super viewDidLoad];
question *quest = [[question alloc] init];
//Parsing code
NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
[request setURL:[NSURL URLWithString:@"http://***/****/fetch.php"]];
[request setHTTPMethod:@"POST"];
NSURLSession *session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration]];
[[session dataTaskWithRequest:request completionHandler:^(NSData *data , NSURLResponse *response , NSError *error){
NSError *err = nil;
id jsonData = [NSJSONSerialization JSONObjectWithData:data options:0 error:&err];
if (err) {
[self alertMessage:(@"%@", err)];
}
else {
//Unclear from here
NSLog(@"%@", jsonData[@"data"]);
allData = jsonData[@"data"];
NSLog(@"%lu",(unsigned long)allData.count);
int count = allData.count;
int i = 0;
while (i < count){
question *que;
NSString *q,*a,*o1,*o2,*o3,*o4;
a = [allData valueForKey:@"answer"];
q = [allData valueForKey:@"question"];
o1 = [allData valueForKey:@"option1"];
o2 = [allData valueForKey:@"option2"];
o3 = [allData valueForKey:@"option3"];
o4 = [allData valueForKey:@"option4"];
//NSLog(@"%@", [allData valueForKey:@"question"]);
[que setValue:q forKey:@"question"];
[que setValue:a forKey:@"answer"];
[que setValue:o1 forKey:@"option1"];
[que setValue:o2 forKey:@"option2"];
[que setValue:o3 forKey:@"option3"];
[que setValue:o4 forKey:@"option4"];
i++;
NSLog(@"%@",[que valueForKey:@"question"]);
}
}
}] resume];
}
以下是NSLog(@"%@", jsonData[@"data"]);
代码在控制台中的输出结果。
{
answer = sometext;
id = 7;
option1 = sometext;
option2 = sometext;
option3 = sometext;
option4 = sometext;
question = "sometext";
},
{
answer = sometext;
id = 9;
option1 = sometext;
option2 = sometext;
option3 = sometext;
option4 = sometext;
question = "sometext";
}
)
据我所知,这个json数据是一个字典数组(?)
我要做的下一步是创建了一个&#34;问题&#34;类。我不确定我是否做得对,但这里是代码:
#import "question.h"
@implementation question {
NSString *q;
NSString *a;
NSString *o1;
NSString *o2;
NSString *o3;
NSString *o4;
}
@end
在viewDidLoad
方法的while循环中,我尝试创建名为question
的{{1}}类的实例,我试图填充该类,如图所示代码。
但是行que
在控制台中提供了NSLog(@"%@",[que valueForKey:@"question"]);
。
我确定我使用的方法有问题。
第二个问题是,我正在创建一个名为null
的{{1}}数组,我在question
之后立即声明。但是,我无法在任何其他代码块中使用它,例如按钮的单击事件。如果我尝试使用quest
上方的viewDidLoad
行,则会出错:
question *quest = [[question alloc] init];
我知道这不是理想的编码方式,但我仍然是这里的初学者,我只是对所有这些新概念感到困惑。我在Swift中开发了相同的应用程序,但Objective C感觉太难了。 任何帮助将不胜感激。
答案 0 :(得分:1)
任务未声明为数组。在类定义中声明数组(在.h文件中)。例如 -
NSMutableArray *questionsArray;
确保在开始尝试在数据解析中添加数据之前对其进行初始化(您应该将解析移动到自己的方法中,而不是在viewDidLoad方法中);
questionsArray = [[NSMutableArray alloc] initWithCapacity:20];
您可以使用键/值属性,但类似于
que.answer = [allData valueForKey:@"question"];
更干净(imo)。解析完问题后,您可以像这样将它添加到数组中;
[questionsArray addObject:que];
答案 1 :(得分:1)
首先要获得你想要的东西,你必须创建一个NSMutableArray,它将存储Question Class的实例,你必须将它声明为像这样的全局数组
<html>
<body>
<p id="demo"></p>
<script>
var firstdate = '2012-11-21';
var seconddate = '2012-11-21';
if( (new Date(firstdate).getTime() > new Date(seconddate).getTime()))
{
document.getElementById("demo").innerHTML = "firstdate is greater";
}
else if( (new Date(firstdate).getTime() < new Date(seconddate).getTime()))
{
document.getElementById("demo").innerHTML = "first date is not greater";
}
else if( (new Date(firstdate).getTime() == new Date(seconddate).getTime()))
{
document.getElementById("demo").innerHTML = "first date is equal";
}
else
{
document.getElementById("demo").innerHTML = "date format is not correct";
}
</script>
</body>
</html>
现在,在question.h中,你必须为这样的所有变量声明@interface MyClass () {
NSMutableArray * arrQuestion;
}
,同样问题类将从NSObject派生,因为你将它创建为@property
类< / p>
Model
现在在while循环中你必须创建Question类的新实例,并且必须像这样分配值
@interface question : NSObject
@property (nonatomic, strong) NSString *strQuestion;
@property (nonatomic, strong) NSString * strAnswer;
@property (nonatomic, strong) NSString * strOptionA;
@property (nonatomic, strong) NSString * strOptionB;
@property (nonatomic, strong) NSString * strOptionC;
@property (nonatomic, strong) NSString * strOptionD;
@end
现在从arrQuestion = [NSMutableArray new];
while (i < count){
question *quest = [[question alloc] init];
quest.strQuestion = [[[jsonData objectForKey:@"data"]objectAtIndex:i] objectForKey:@"question"];
quest.strAnswer = [[[jsonData objectForKey:@"data"]objectAtIndex:i] objectForKey:@"answer"];
quest.strOptionA = [[[jsonData objectForKey:@"data"]objectAtIndex:i] objectForKey:@"option1"];
quest.strOptionB = [[[jsonData objectForKey:@"data"]objectAtIndex:i] objectForKey:@"option2"];
quest.strOptionC = [[[jsonData objectForKey:@"data"]objectAtIndex:i] objectForKey:@"option3"];
quest.strOptionD = [[[jsonData objectForKey:@"data"]objectAtIndex:i] objectForKey:@"option4"];
i++;
[arrQuestion addObject:quest];
}
您可以访问像这样的值
arrQuestion