使用JSONKit将字符串，字典，数组转换成json格式

NSString *str = nil;
//字符串
NSMutableString *string = [[NSMutableString alloc] init];
[string appendString:@"xxxx"];
str = [string JSONString];
NSLog(@"str1:%@",[NSString stringWithString:str]);

//数组
NSArray *array = [[NSArray alloc] initWithObjects:@"111",@"333",@"222", nil];
// NSMutableArray *array = [NSMutableArray array];
str = [array JSONString];
NSLog(@"str2:%@",[NSString stringWithString:str]);
[array release ];

//字典
NSArray *firstArr = [NSArray arrayWithObjects:@"first",@"second", nil];
//基本数据类型转换成NSNumber类型
NSArray *secondArr = [NSArray arrayWithObjects:[NSNumber numberWithDouble:2.1],[NSNumber numberWithBool:NO], nil];
//加到字典中
NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:firstArr,@"first",secondArr,@"second", nil];
//转化成json格式
str = [dic JSONString];
NSString *str2 = [NSString stringWithString:str];
NSLog(@"str3:%@",str2);

//编码
NSData *archive = [NSKeyedArchiver archivedDataWithRootObject:array];
// NSLog(@"archive:%@",archive);
NSArray *arr2 = [NSKeyedUnarchiver unarchiveObjectWithData:archive];
NSLog(@"arr2:%@",arr2);

// 将数组转JSON
- (NSData *)toJSONData:(id)theData{
NSError *error = nil;
NSData *jsonData = [NSJSONSerialization dataWithJSONObject:theData
options:NSJSONWritingPrettyPrinted
error:&error];
if ([jsonData length] > 0 && error == nil){
return jsonData;
}else{
return nil;
}
}

NSString *jsonString = [[NSString alloc] initWithData:jsonData  encoding:NSUTF8StringEncoding];