创建 NSDictionary

Posted 2023-03-16

【中文标题】创建 NSDictionary

【英文标题】：Creating NSDictionary

【发布时间】：2016-06-03 12:43:12

【问题描述】：

我如何创建字典，当我用它创建 jsondata 时，json 看起来像：

 "historyStep":[


"counter": "50",
"timestamp": "1461674383632"

 ]

我这样做了：

NSMutableDictionary*jsonDictOth = [[NSMutableDictionary alloc]init];
[jsonDictOth setObject:@(810) forKey:@"counter"];
[jsonDictOth setObject:@"1464957395241.447998" forKey:@"timestamp"];
NSMutableDictionary *jsonDictMain = [[NSMutableDictionary alloc]initWithObjectsAndKeys:jsonDictOth,@"historyStep", nil];
NSError*error;
NSData *data = [NSJSONSerialization dataWithJSONObject:jsonDictMain
                                                   options:NSJSONWritingPrettyPrinted
                                                     error:&error];

但看起来：

 historyStep =     
    counter = 810;
    timestamp = "1464957395241.447998";
;

【问题讨论】：

NSMutableDictionary *jsonDictMain 创建一个数组而不是这个字典

您缺少一个级别：NSDictionary（***），在***键“historyStep”中带有 NSDictionary 的 NSArray。

【参考方案1】：

您缺少一个级别：NSDictionary（***）与 NSArray 的 NSDictionary 在***键 historyStep：

NSMutableDictionary *topLevel = [[NSMutableDictionary alloc] init];


NSArray *historySteps = [[NSMutableArray alloc] init];
//Here you may have a for loop in case there are more steps
NSDictionary *aStep = @@"counter":@"50", @"timestamp":@"1461674383632";
[historySteps addObject:aStep]

[topLevel setObject:historySteps forKey@"historyStep"];

NSError*error;
NSData *data = [NSJSONSerialization dataWithJSONObject:topLevel
                                               options:NSJSONWritingPrettyPrinted
                                                 error:&error];

【参考方案2】：

NSDictionary *innerDictionary = [[NSDictionary alloc]initWithObjectsAndKeys:@"50", @"counter",@"1461674383632", @"timestamp", nil];
NSArray *array = [[NSArray alloc]initWithObjects:innerDictionary, nil];
NSDictionary *outerDict = [[NSDictionary alloc]initWithObjectsAndKeys:array, @"historyStep", nil];

使用此代码将完美运行。

【讨论】：

为什么这么冗长？ Objective-C 文字有什么问题？

【参考方案3】：

你的代码应该是这样的，

   NSMutableDictionary*jsonDictOth = [[NSMutableDictionary alloc]init];
[jsonDictOth setObject:@(810) forKey:@"counter"];
[jsonDictOth setObject:@"1464957395241.447998" forKey:@"timestamp"];

NSMutableArray *arr = [[NSMutableArray alloc]init];

[arr addObject:jsonDictOth];

NSMutableDictionary *jsonDictMain = [[NSMutableDictionary alloc]initWithObjectsAndKeys:arr,@"historyStep", nil];
NSLog(@"jsonMain is %@",jsonDictMain);
NSError*error;
NSData *data = [NSJSONSerialization dataWithJSONObject:jsonDictMain
                                               options:0
                                                 error:&error];

它的输出是，

jsonMain is 
historyStep =     (
            
        counter = 810;
        timestamp = "1464957395241.447998";
    
 );

你只是错过了一个数组