小编Kar*_*ick的帖子

我正在尝试写一个宏来确定该设备是3.5英寸还是4英寸.下面有类似的东西.

    #define IOS_OLDER_THAN_6 ( [ [ [ UIDevice currentDevice ] systemVersion ] floatValue ] < 6.0 )
    #define IOS_NEWER_OR_EQUAL_TO_6 ( [ [ [ UIDevice currentDevice ] systemVersion ] floatValue ] >= 6.0 )

有人能帮我吗.请

我想从基于id的coredata中获取记录.因为我在每次迭代的for循环中获取执行时间非常大.有人可以告诉我如何有效地做到这一点.

 for (int i = 0; i < [tempCodeDescArray count]; i++) {
        NSDictionary *codeDescDict = [tempCodeDescArray objectAtIndex:i];
        NSPredicate *predicate=[NSPredicate predicateWithFormat:@"itemId=%@",[codeDescDict valueForKey:@"itemId"]];
        [fetchRequest setPredicate:predicate];
        NSError *error=nil;
         NSArray *result=[context executeFetchRequest:fetchRequest error:&error];
    }