JSONKit 使用示例

JSONKit是Object-C一个处理json数据的库，非常高效而且易用，对比同类型的库有非常明显的性能优势，见下图：

JSON和Object-C中数据类型的映射关系如下表所示

JSONObjective-CnullNSNulltrue and falseNSNumberNumberNSNumberStringNSStringArrayNSArrayObjectNSDictionary

下面写一个简单的程序使用一下JSONKit（只需下载头文件以及源文件，放在项目目录下）

#import <Foundation/Foundation.h>#import "lib/JSONKit.h"int main (int argc, const char * argv[]) {    NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];NSString *res = nil;/* * json格式编码 *///字符串NSString *str = @"this is a nsstring";res = [str JSONString];NSLog(@"res= %@", [NSString stringWithString: res]);//res= "this is a nsstring"//数组NSArray *arr = [[NSArray alloc] initWithObjects:@"One",@"Two",@"Three",nil];res = [arr JSONString];NSLog(@"res= %@", [NSString stringWithString: res]);[arr release];//res= ["One","Two","Three"]//字典类型（对象）NSArray *arr1 = [NSArray arrayWithObjects:@"dog",@"cat",nil];NSArray *arr2 = [NSArray arrayWithObjects:[NSNumber numberWithBool:YES],[NSNumber numberWithInt:30],nil];NSDictionary *dic = [NSDictionary dictionaryWithObjectsAndKeys:arr1,@"pets",arr2,@"other",nil];res = [dic JSONString];NSLog(@"res= %@", [NSString stringWithString: res]);//res= {"pets":["dog","cat"],"other":[true,30]}    /* * json格式解码 */JSONDecoder *jd=[[JSONDecoder alloc] init];//针对NSData数据NSData *data = [dic JSONData];NSDictionary *ret = [jd objectWithData: data];NSLog(@"res= %@", [ret objectForKey:@"pets"]);//res= (    //dog,    //cat//)NSLog(@"res= %@", [[ret objectForKey:@"other"] objectAtIndex:0]);//res= 1//针对NSString字符串数据NSString *nstr = [dic JSONString];NSDictionary *ret2 = [jd objectWithUTF8String:(const unsigned char *)[nstr UTF8String] length:(unsigned int)[nstr length]];NSLog(@"res= %d", [[ret2 objectForKey:@"pets"] indexOfObject:@"cat"]);//res= 1NSLog(@"res= %@", [[ret2 objectForKey:@"other"] objectAtIndex:1]);//res= 30[jd release];    [pool drain];    return 0;}

JSONKit的接口中还可以自行定制序列化和反序列化选项，针对如何提升效率作者也是给了很多使用的建议，例如尽量使用NSData来替换NSString类型，因为JSON数据通常是用来通信使用，而通信过程使用NSData类型更为高效，毕竟是二进制流数据更短，所以没必要转成NSString多此一举了。不知道我理解得对不对。