Question

我在ARC中使用自定义委托类时遇到了一个奇怪的问题。在viewDidLad之后的viewcontroller中，我调用工具栏setDelegate方法并将viewcontroller指定为委托。

每当我尝试引用委托时，它都是零，即使在设置之后也是如此视图控制器。

//MPToolbar.h

#import <UIKit/UIKit.h>

//Define the protocol for the delegate
@class MPToolBar;
@protocol MPToolBarDelegate <NSObject>
@required
- (void)writeButtonSelected;
- (void)writeButtonDeSelected;
@end

@interface MPToolBar : UIView{
    id <MPToolBarDelegate> delegate;
}

@property(strong) UIButton *lastButton;

@property(strong) id <MPToolBarDelegate> delegate;
-(IBAction)buttonSelected:(id)sender;
-(void)resizeForOrientation:(UIInterfaceOrientation)orientation;

@end

//MPToolbar.m
#import "MPToolBar.h"

@implementation MPToolBar
@synthesize lastButton, delegate;

- (id)initWithFrame:(CGRect)frame
{
    if ((self = [super initWithFrame:frame])) {
        // Initialization code
    }
    NSArray *nibViews = [[NSBundle mainBundle] loadNibNamed:@"MPToolBar" owner:self options:nil];
    [self addSubview:[nibViews objectAtIndex:0]];
    return self;
}


#pragma button actions
-(IBAction)buttonSelected:(id)sender{
    UIButton *btn = (UIButton *)sender;
    if(lastButton && lastButton != btn)[self deselect:lastButton];

    if (btn.selected){
        [self deselect:btn];
        return;
    }

    [btn setSelected:YES];
    lastButton = btn;
    switch (btn.tag) {
        case 0:
            [self.delegate writeButtonSelected];
            break;
    }
}
-(void)deselect:(UIButton *)btn{
    [btn setSelected:NO];
    switch (btn.tag) {
        case 0:
            [self.delegate writeButtonDeSelected];
            break;
    }
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect
{
    // Drawing code
}
*/
-(void)resizeForOrientation:(UIInterfaceOrientation)orientation{
    if (UIInterfaceOrientationIsLandscape(orientation)) {
        self.frame = CGRectMake(0, 44, 1024, 60);
    }
    if (UIInterfaceOrientationIsPortrait(orientation)) {
        self.frame = CGRectMake(0, 44, 768, 60);
    }
}
@end

//ViewTest.h
#import <UIKit/UIKit.h>
#import "MPToolBar.h"
@interface ViewTest : UIViewController <MPToolBarDelegate>
{
    MPToolBar *toolBar;
}
@property(strong) MPToolBar *toolBar;
@end

//ViewTest.m
#import "ViewTest.h"

@interface ViewTest ()

@end

@implementation ViewTest
@synthesize toolBar;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    self.toolBar = [[MPToolBar alloc] initWithFrame:CGRectMake(0, 44, 1024, 60)];
    [self.view addSubview:self.toolBar];
    [self.toolBar setAlpha:1.0];
    [self.toolBar setDelegate:self];
    // Do any additional setup after loading the view from its nib.
}
#pragma mark - MPToolBar Delegate Methods
-(void)writeButtonSelected{
    //set new annotation for write mode and size to screen bounds.
    NSLog(@"writeButtonSelected");
}
- (void)writeButtonDeSelected{
    NSLog(@"writeButtonDeSelected");
}
- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

@end

Answer 1

好的，所以我终于找到了问题。在我的xib文件中，我将UIView类设置为我的自定义控件类名，而不是设置文件所有者。

一旦我将xib中的第一个UIView更改回标准的UIView，然后将文件所有者设置为我的自定义类，那么对于世界来说再次正确！

- 谢谢所有试图提供帮助的人！

Answer 2

可能导致问题的几件事情：

您是否在其标题中将视图控制器声明为MPToolBarDelegate？（该代码不存在）。
这些是代码中的委托函数：

-(void)ButtonSelected;

-(void)ButtonDeSelected;

但是，你实际上是在调用这个：

[_delegate writeButtonSelected];

这不属于您的协议。

Answer 3

尝试更改您的委托声明：

@interface MPToolBar : UIView{
    id delegate;
}

@property (nonatomic, assign) id <MPToolBarDelegate> delegate;

然后当你调用你的委托方法时，请使用：

[self.delegate ButtonSelected];

此外，原始iPad可升级至iOS 5.0。如果您使用的是ARC，那么无论如何都不能与4.3兼容，根据我的理解，ARC仅从5.0开始。

Answer 4

对我来说有类似的症状，我的问题是segue的destinationViewController不是我期望它的对象，因为它嵌入在UINavigationController中。

轻松修复。看这里。 Lose pointer to Delegate while going through Navigation Controller

iOS自定义委托从viewController调用setDelegate后返回Nil

4 个答案: