通过引用传递 UIButton

Question

我正在尝试创建一个 "helper class" 来为 UI 元素设置动画，但我没有成功。我应该说我仍然是 iOS 编程的初学者，我喜欢以编程方式做任何事情。

我正在做的是：

 Animator *anim;
 myButton = [UIButton buttonWithType:UIButtonTypeRoundedRect]; 
[myButton addTarget:self action:@selector(addToFav) forControlEvents:UIControlEventTouchUpInside];
[myButton setTitle:@"+" forState:UIControlStateNormal];
[myButton setFont:[UIFont systemFontOfSize:23]];
[myButton setBackgroundColor:[UIColor greenColor]];
[myButton setFrame:CGRectMake(screenWidth * 0.9 - (SizeX / 2), screenHeight * 0.2285 - (SizeY / 2), X, Y)];
[self.view addSubview: myButton];
[anim moveButton:&myButton alongX:-100 alongY:200 withTime:1.5];

这是

Animator.h

@interface Animator : NSObject

-(void)moveButton:(UIButton*)button alongX:(int)x alongY:(int)y withTime:(float)time;
-(void)scaleButton:(UIButton*)button width:(float)width height:(float)height withTime:(float)time;

@end

Animator.m

@implementation Animator

-(void)moveButton:(UIButton*)button alongX:(int)x alongY:(int)y withTime:(float)time
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDuration:time];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [button setFrame:CGRectMake(button.frame.origin.x + x, button.frame.origin.y + y, button.frame.size.width, button.frame.size.height)];
    [UIView commitAnimations];
}

-(void)scaleButton:(UIButton*)button width:(float)width height:(float)height withTime:(float)time
{
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationDuration:time];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [button setFrame:CGRectMake(button.frame.origin.x, button.frame.origin.y, button.frame.size.width * width, button.frame.size.height * height)];
    [UIView commitAnimations];
}

@end

编译器告诉我不可能传递 UIButton 的地址，因为 ARC，我不想禁用它，我什至不知道它会有多大帮助禁用 ARC。

有什么方法可以通过引用传递UI按钮吗？

测试代码：

#import "ViewController.h"
#import "Animator.h"

@interface ViewController ()
{
    UIButton* myButton;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib

    myButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [myButton addTarget:self action:@selector(move) forControlEvents:UIControlEventTouchUpInside];
    [myButton setTitle:@"+" forState:UIControlStateNormal];
    [myButton setFont:[UIFont systemFontOfSize:23]];
    [myButton setBackgroundColor:[UIColor greenColor]];
    [myButton setFrame:CGRectMake(0, 0, 100, 100)];
    [self.view addSubview: myButton];

}
-(void)move
{
    Animator *anim;
    [anim moveButton:myButton alongX:-100 alongY:200 withTime:1.5];


    /*[UIView animateWithDuration:1.5 animations:^{ // animate
        myButton.frame = CGRectOffset(myButton.frame, 0, 200); // set new frame but with specified offset
    }];*/
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end

Answer 1

改用这个：

[anim moveButton:myButton alongX:-100 alongY:200 withTime:1.5]; // no asterisk!

请注意，我相信您已经像这样初始化了 myButton：

UIButton *myButton = [[UIButton alloc] init];

是一个指针而不是对象本身。所以使用 &myButton 意味着：获取指针的地址！但是如您所见，您不需要指针的地址，而是按钮的地址。只需传递 myButton，因为它已经是指向 myButton 的指针。

另一种方法

这里有一个简单的代码片段，应该适合您。如果不是，问题出在其他地方。

-(void)moveButton:(UIButton*)button alongX:(int)x alongY:(int)y withTime:(float)time 
{
    [UIView animateWithDuration:time animations:^{ // animate
        button.frame = CGRectOffset(button.frame, x, y); // set new frame but with specified offset
    }];
}

提示：将方法签名更改为此

-(void)moveButton:(UIButton*)button alongX:(CGFloat)x alongY:(CGFloat)y withTime:(CGFloat)time;
-(void)scaleButton:(UIButton*)button width:(CGFloat)width height:(CGFloat)height withTime:(CGFloat)time;

希望这是您的解决方案:)

Animator *anim = [[Animator alloc] init];
[anim moveButton:myButton alongX:-100 alongY:200 withTime:1.5];

Answer 2

对于您提供的示例，我认为您实际上不需要通过引用传递按钮。 Animator 上的方法采用指向 UIButton 的指针，myButton 匹配该指针。如果你想重新分配指针，你只需要通过引用传递一个对象，Animator目前不这样做。

我认为您只需将 moveButton:&myButton 更改为 moveButton:myButton。

话虽这么说，如果您做过想要通过引用传递指针（通常使用 NSError 输出参数），您需要将签名更改为使用双指针并像您所做的那样使用 & 运算符传入。

以NSFileManager的remoteItemAtURL:error:方法的签名为例。

NSError *error = nil;
[[NSFileManager defaultManager] removeItemAtURL:url error:&error];

// error could now be pointing to something other than nil

（参见 https://developer.apple.com/library/prerelease/ios/documentation/Cocoa/Reference/Foundation/Classes/NSFileManager_Class/index.html#//apple_ref/occ/instm/NSFileManager/removeItemAtURL:error:)

通过引用传递 UIButton

Pass UIButton by reference

objective-c

pass-by-reference

uibutton

ios