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我想创建一个可以反复重用的库，以加快我的开发速度，如果我愿意，可以添加到新项目中。基本上我想建立一个抽象层。有人可以告诉我如何做到这一点以及为什么这部分代码：

  if ([self.delegate respondsToSelector:@selector(enableCamera)]) {
        BOOL enabled;
        enabled = [self.delegate enableCamera];
        if (enabled == YES) {
            [self enableCameraMethod];

        }

不叫？

下面是我的代码：

图书馆.h：

@protocol usesCamera <NSObject>
@optional
-(BOOL)enableCamera;
@end

@interface Library : NSObject

@property (nonatomic, weak) id <usesCamera> delegate;
-(void)enableCameraMethod;
@end

图书馆.m

#import "Library.h"

@implementation Library

- (id) init
{
if (self = [super init]) {        
    if ([self.delegate respondsToSelector:@selector(enableCamera)]) {
        BOOL enabled;
        enabled = [self.delegate enableCamera];
        if (enabled == YES) {
            [self enableCameraMethod];

        }
    }
    return (self);

}
}

-(void)enableCameraMethod {
NSLog(@"Implement my camera method here");
}
@end

UIViewController.h

#import <UIKit/UIKit.h>
#import "Library.h"


@interface ViewController : UIViewController <usesCamera>

@end

UIViewController.m

#import "ViewController.h"
#import "Library.h"

@interface ViewController ()

@property (nonatomic, strong) UIViewController *myVC;

@end

@implementation ViewController

-(BOOL)enableCamera {
return YES;
}

- (void)viewDidLoad
{
[super viewDidLoad];

Library *myLibrary = [[Library alloc] init];

// Do any additional setup after loading the view, typically from a nib.
 }

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

@end
4

1 回答 1

1

您是否在 ViewController 类中为 myLibrary 实例设置了委托。你必须做这样的事情：

Library *myLibrary = [[Library alloc] init];
myLibrary.delegate = self;

由于在设置委托之前调用了 init，因此它可能不起作用，而不是在 init 函数中定义逻辑，而是创建另一个方法并在设置委托后调用此方法。

于 2012-10-22T04:26:22.370 回答