iOS对象（字典或数组）转化为JSon字符串

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

[dictionary setValue:@"hello" forKey:@"one"];

[dictionary setValue:@"world" forKey:@"two"];

NSArray *arry=[NSArray arrayWithObjects:@"001",@"002",@"003", nil];

[dictionary setValue:arry forKey:@"three"];

NSData *data=[NSJSONSerialization dataWithJSONObject:dictionary options:NSJSONWritingPrettyPrinted error:nil];

NSString *jsonStr=[[NSString alloc]initWithData:dataencoding:NSUTF8StringEncoding];

NSLog(@"jsonStr==%@",jsonStr);

输出结果为：

str=={

"one" : "hello",

"two" : "world",

"three" : [

"001",

"002",

"003"

]

}