objective-c – 如何创建自己的方法,以块为参数,稍后可以调用？

发布时间：2020-12-16 07:51:34 所属栏目：百科来源：网络整理

导读：如何创建自己的方法,以块为参数,稍后可以调用？我试过以下事情. #import UIKit/UIKit.htypedef void (^viewCreator)(void);@interface blocks2ViewController : UIViewController{}-(void)createButtonUsingBlocks:(viewCreator *)block;@end- (void)viewDi

如何创建自己的方法,以块为参数,稍后可以调用？

我试过以下事情.

#import <UIKit/UIKit.h>
typedef void (^viewCreator)(void);

@interface blocks2ViewController : UIViewController
{
}
-(void)createButtonUsingBlocks:(viewCreator *)block;

@end


- (void)viewDidLoad {
  [super viewDidLoad];
  [self createButtonUsingBlocks:^(NSString * name) {
        UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50,50,200,100)];
        dummyButton.backgroundColor = [UIColor greenColor];
        [self.view addSubview:dummyButton];
  }];
}

-(void)createButtonUsingBlocks:(viewCreator *)block
{
    //    Do something
    NSLog(@"inside creator");
}

我也试图将块变量传递给我的自定义方法,但没有任何成功.为什么是这样,什么是正确的方法呢？

更新

这是文件is.h：

#import <UIKit/UIKit.h>

typedef void (^viewCreator)(void);

@interface blocks2ViewController : UIViewController
{

}
- (void)createButtonUsingBlocks:(viewCreator)block;
@end

这是.m文件：

#import "blocks2ViewController.h"

@implementation blocks2ViewController
// Implement viewDidLoad to do additional setup after loading the view,typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
        [self createButtonUsingBlocks:^(NSString * name) {
        UIButton *dummyButton = [[UIButton alloc]initWithFrame:CGRectMake(50,100)];
        dummyButton.backgroundColor = [UIColor greenColor];
        [self.view addSubview:dummyButton];
        [dummyButton release];
    }];
}

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data,images,etc that aren't in use.
}

- (void)viewDidUnload {
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

// ...

-(void)createButtonUsingBlocks:(viewCreator)block
{
//    viewCreator;
    NSLog(@"inside creator");
}
@end

解决方法

首先,如果要让您的块获取字符串参数,则typedef为关闭：

typedef void (^viewCreator)(NSString*);

其次,块的类型是：

ReturnType (^)(ParameterTypes...)

并不是

ReturnType (^*)(ParameterTypes...)

因此,不需要添加指向viewCreator类型的指针：

- (void)createButtonUsingBlocks:(viewCreator)block;

第三,你实际上必须调用块,如果你还没有这样做：

-(void)createButtonUsingBlocks:(viewCreator *)block {
    block(@"button name");
    // ...

第四和最后,UIButton被过度保留 – 你应该释放或自动释放它：

UIButton *dummyButton = [[UIButton alloc] initWithFrame:...];
// ...    
[self.view addSubview:dummyButton];
[dummyButton release];

一起投掷所有的东西：

#import <UIKit/UIKit.h>
typedef void (^viewCreator)(NSString*);

@interface blocks2ViewController : UIViewController {}
-(void)createButtonUsingBlocks:(viewCreator)block;      
@end

@implementation blocks2ViewController
- (void)viewDidLoad {
    [super viewDidLoad];  
    [self createButtonUsingBlocks:^(NSString *name) {
        UIButton *dummyButton = 
            [[UIButton alloc] initWithFrame:CGRectMake(50,100)];
        dummyButton.backgroundColor = [UIColor greenColor];
        [self.view addSubview:dummyButton];
        [dummyButton release];
    }];
}

-(void)createButtonUsingBlocks:(viewCreator)block {
    block(@"my button name");
}
@end

（编辑：李大同）

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