使用CGRectZero初始化UIView的框架

我找到了一个关于如何做某事的教程 Swift .我在一个 Objective-C 项目,我已经尝试将类导入 目标-C 但是 that's been a bug-riddled, time monopolizing disaster ,所以我将Swift转换为Objective-C。

我得到了 UIView.h/m 到没有警告/错误的程度,但将视图添加到 UIViewController 是另一回事。我已经在下面发布了我试图“翻译”的初始化代码。我欢迎输入关于我所犯的错误。

用于初始化UIView的Swift类代码:

var parentFrame :CGRect = CGRectZero

override init(frame: CGRect) {
    super.init(frame: frame)
    backgroundColor = Colors.clear
}

用于初始化UIView的“翻译”Objective-C类中的代码

myUIView.h

// At MartinR's suggestion, I removed the pointer here
@property (nonatomic) CGRect parentFrame;

myUIView.m

// No compiler errors -- the errors occur on the UIViewController
- (instancetype)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:(self.parentFrame)];
    self.parentFrame = CGRectZero;
    if (self) {
        [super setFrame:self.parentFrame];
        self.backgroundColor = [UIColor whiteColor];
    }
    return self;
}

当我尝试将UIView添加到UIViewController时,出现了问题。我无法理解为什么我会收到以下警告:

Swift UIViewController代码,用于添加UIView

  func addHolderView() {
    let boxSize: CGFloat = 75.0
    holderView.frame = CGRect(x: view.bounds.width / 2 - boxSize / 2,
                              y: view.bounds.height / 2 - boxSize / 2,
                              width: boxSize,
                              height: boxSize)
    holderView.parentFrame = view.frame
    holderView.delegate = self
    view.addSubview(holderView)
    holderView.addOval()
  }

我的“翻译”Objective-C ViewController充斥着实现错误

myUIViewController.h

#import "HolderView.h"

// blah blah

@property (nonatomic, strong) HolderView *holderView;

myUIViewController.m

- (void)addHolderView {
    CGFloat boxSize = 75.0;
// WARNING: The following line says "expression result unused"
    [self.holderView initWithFrame:CGRectMake(_view.bounds.size.width / 2 - boxSize / 2,
                                              _view.bounds.size.height / 2 - boxSize / 2,
                                              boxSize,
                                              boxSize)];
    // Warning here went away by removing the pointer on CGRect parentFrame
    self.holderView.parentFrame = view.frame;
    self.holderView.delegate = self; // I have the delegate stuff squared away
    [self.view addSubview:self.holderView];
}

感谢您的阅读。

更新以反映MartinR在评论中的意见。

我更新了上面的代码以删除 CGRect parentFrame .