在 iOS 中从 NSDictionary 生成 JSON 字符串

Generate JSON string from NSDictionary in iOS

提问by ChandraSekhar

I have a dictionaryI need to generate a JSON stringby using dictionary. Is it possible to convert it? Can you guys please help on this?

我有一个dictionary我需要JSON string使用dictionary. 可以转换吗？你们能帮忙解决这个问题吗？

采纳答案by Ben Clayton

Here are categories for NSArray and NSDictionary to make this super-easy. I've added an option for pretty-print (newlines and tabs to make easier to read).

这里是 NSArray 和 NSDictionary 的类别，使这个超级简单。我为漂亮打印添加了一个选项（换行符和制表符，以便于阅读）。

@interface NSDictionary (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint;
@end

.

.

@implementation NSDictionary (BVJSONString)

  -(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint {
     NSError *error;
     NSData *jsonData = [NSJSONSerialization dataWithJSONObject:self
                                                   options:(NSJSONWritingOptions)    (prettyPrint ? NSJSONWritingPrettyPrinted : 0)
                                                     error:&error];

     if (! jsonData) {
        NSLog(@"%s: error: %@", __func__, error.localizedDescription);
        return @"{}";
     } else {
        return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
     } 
 }
@end

.

.

@interface NSArray (BVJSONString)
- (NSString *)bv_jsonStringWithPrettyPrint:(BOOL)prettyPrint;
@end

.

.

@implementation NSArray (BVJSONString)
-(NSString*) bv_jsonStringWithPrettyPrint:(BOOL) prettyPrint {
    NSError *error;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:self
                                                       options:(NSJSONWritingOptions) (prettyPrint ? NSJSONWritingPrettyPrinted : 0)
                                                         error:&error];

    if (! jsonData) {
        NSLog(@"%s: error: %@", __func__, error.localizedDescription);
        return @"[]";
    } else {
        return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    }
}
@end

回答by Guillaume

Apple added a JSON parser and serializer in iOS 5.0 and Mac OS X 10.7. See NSJSONSerialization.

Apple 在 iOS 5.0 和 Mac OS X 10.7 中添加了 JSON 解析器和序列化器。请参阅NSJSONSerialization。

To generate a JSON string from a NSDictionary or NSArray, you do not need to import any third party framework anymore.

要从 NSDictionary 或 NSArray 生成 JSON 字符串，您不再需要导入任何第三方框架。

Here is how to do it:

这是如何做到的：

NSError *error; 
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dictionaryOrArrayToOutput 
                                                   options:NSJSONWritingPrettyPrinted // Pass 0 if you don't care about the readability of the generated string
                                                     error:&error];

if (! jsonData) {
    NSLog(@"Got an error: %@", error);
} else {
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
}

回答by jobima

To convert a NSDictionary to a NSString:

要将 NSDictionary 转换为 NSString：

NSError * err;
NSData * jsonData = [NSJSONSerialization dataWithJSONObject:myDictionary options:0 error:&err]; 
NSString * myString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];

回答by Nick Weaver

NOTE: This answer was given before iOS 5 was released.

注意：这个答案是在 iOS 5 发布之前给出的。

Get the json-frameworkand do this:

获取json-framework并执行以下操作：

#import "SBJsonWriter.h"

...

SBJsonWriter *jsonWriter = [[SBJsonWriter alloc] init];

NSString *jsonString = [jsonWriter stringWithObject:myDictionary];  

[jsonWriter release];

myDictionarywill be your dictionary.

myDictionary将是你的字典。

回答by Andy

You can also do this on-the-fly by entering the following into the debugger

您也可以通过在调试器中输入以下内容来即时执行此操作

po [[NSString alloc] initWithData:[NSJSONSerialization dataWithJSONObject:yourDictionary options:1 error:nil] encoding:4];

回答by Meet Doshi

You can pass array or dictionary. Here, I am taking NSMutableDictionary.

您可以传递数组或字典。在这里，我正在使用 NSMutableDictionary。

NSMutableDictionary *contentDictionary = [[NSMutableDictionary alloc]init];
[contentDictionary setValue:@"a" forKey:@"b"];
[contentDictionary setValue:@"c" forKey:@"d"];

To generate a JSON string from a NSDictionary or NSArray, You don't need to import any third party framework. Just use following code:-

要从 NSDictionary 或 NSArray 生成 JSON 字符串，您不需要导入任何第三方框架。只需使用以下代码：-

NSError *error; 
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:contentDictionary // Here you can pass array or dictionary
                    options:NSJSONWritingPrettyPrinted // Pass 0 if you don't care about the readability of the generated string
                    error:&error];
NSString *jsonString;
if (jsonData) {
    jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    //This is your JSON String
    //NSUTF8StringEncoding encodes special characters using an escaping scheme
} else {
    NSLog(@"Got an error: %@", error);
    jsonString = @"";
}
NSLog(@"Your JSON String is %@", jsonString);

回答by user2885077

NSMutableDictionary *contentDictionary = [[NSMutableDictionary alloc]init];
        [contentDictionary setValue:@"a" forKey:@"b"];
        [contentDictionary setValue:@"c" forKey:@"d"];
        NSData *data = [NSJSONSerialization dataWithJSONObject:contentDictionary options:NSJSONWritingPrettyPrinted error:nil];
        NSString *jsonStr = [[NSString alloc] initWithData:data
                                                  encoding:NSUTF8StringEncoding];

回答by King-Wizard

In Swift (version 2.0):

在Swift（2.0 版）中：

class func jsonStringWithJSONObject(jsonObject: AnyObject) throws -> String? {
    let data: NSData? = try? NSJSONSerialization.dataWithJSONObject(jsonObject, options: NSJSONWritingOptions.PrettyPrinted)

    var jsonStr: String?
    if data != nil {
        jsonStr = String(data: data!, encoding: NSUTF8StringEncoding)
    }

    return jsonStr
}

回答by mahesh chowdary

Now no need third party classes ios 5 introduced Nsjsonserialization

现在不需要第三方类 ios 5 引入了 Nsjsonserialization

NSString *urlString=@"Your url";
NSString *urlUTF8 = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSURL *url=[[NSURL alloc]initWithString:urlUTF8];
NSURLRequest *request=[NSURLRequest requestWithURL:url];

NSURLResponse *response;

NSData *GETReply = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:nil];

NSError *myError = nil;

NSDictionary *res = [NSJSONSerialization JSONObjectWithData:GETReply options:NSJSONReadingMutableLeaves|| NSJSONReadingMutableContainers error:&myError];

Nslog(@"%@",res);

this code can useful for getting jsondata.

此代码可用于获取 jsondata。

回答by James Laurenstin

In Swift, I've created the following helper function:

在 Swift 中，我创建了以下辅助函数：

class func nsobjectToJSON(swiftObject: NSObject) {
    var jsonCreationError: NSError?
    let jsonData: NSData = NSJSONSerialization.dataWithJSONObject(swiftObject, options: NSJSONWritingOptions.PrettyPrinted, error: &jsonCreationError)!

    if jsonCreationError != nil {
        println("Errors: \(jsonCreationError)")
    }
    else {
        // everything is fine and we have our json stored as an NSData object. We can convert into NSString
        let strJSON : NSString =  NSString(data: jsonData, encoding: NSUTF8StringEncoding)!
        println("\(strJSON)")
    }
}