通過比較是否等於nil。
////?main.m
//?字典
//
//?Created?by?dushengduan?on?15/6/28.
//?Copyright?(c)?2015年?dushengduan.?All?rights?reserved.
//
#import?<Foundation/Foundation.h>
int?main(int?argc,?const?char?*?argv[])?{
NSDictionary?*dic2=[NSDictionary?dictionaryWithObjectsAndKeys:nil,@"key2",@"value3",@"key3",?nil];
//通過key獲取value值
NSObject?*objNew=[dic2?objectForKey:@"key2"];
if?(objNew?==?nil)?{
NSLog(@"value值為空。");
}
return?0;
}