iphone - 如何使用 NSObject 子类？

Question

所以我创建了一个名为 NSObject 的子类Query

@interface Query : NSObject

@property (nonatomic, assign) NSNumber *weight;
@property (nonatomic, assign) NSNumber *bodyFat;
@property (nonatomic, assign) NSNumber *activityLevel;

@end

这对于设置对象的属性是否正确？

在 VC1 中：

BodyFatViewController *aViewController = [[BodyFatViewController alloc]init];
aViewController.query = self.query;
[self.navigationController pushViewController:aViewController animated:YES];

在 VC2 中：

- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    Query *anQuery = [[Query alloc]init];
    anQuery.bodyFat = [self.bodyFatArray objectAtIndex:row];
    anQuery.weight = self.query.weight;
    self.query = anQuery;
}

Answer 1

在两个 VC 之间共享一个对象是非常自然的：

在 VC1 中：

@property (strong, nonatomic) Query *query;
@synthesize query=_query;

// init it
self.query = [[Query alloc] init];
self.query.weight = [NSNumber numberWithInt:150];

// when it's time to present VC2:
BodyFatViewController *aViewController = [[BodyFatViewController alloc]init];
aViewController.query = self.query;
[self.navigationController pushViewController:aViewController animated:YES];

然后在VC2中：

// this is in the public interface in VC2.h
//
@property (strong, nonatomic) Query *query;

不要在 VC2 中分配/初始化它。VC1做到了！！ 但请随意设置或覆盖值...

self.query.bodyFat = [NSNumber numberWithFloat:0.5];

Answer 2

不要创建新查询，只需使用以下属性：

self.query.bodyFat = [self.bodyFatArray objectAtIndex:row];

Answer 3

是的，这是正确的。

self.query = newQueryObject

或者

myBodyFatViewController.query = newQueryObject

两者都有效。