查询单词里面包含“ang”的字符串
NSArray *array = [[NSArray alloc]initWithObjects:@"beijing",@"shanghai",@"guangzou",@"wuhan", nil];
NSString *string = @"ang";
NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF CONTAINS %@",string];
NSLog(@"%@",[array filteredArrayUsingPredicate:pred]); ;