iOS很重要的 block回调

刚刚进入ios开发行业，发现开发中要用到大量的block回调，由此可见它的重要性。学习它之前我也是网上找的资料，推荐这篇文章http://blog.csdn.net/mobanchengshuang/article/details/11751671，我也是从这里得到一点启示。假设对block的使用还不熟悉建议先看我的block那篇文章。以下我用自己的project来解释一下block回调函数。

一、先创建一个简单的xcodeproject

ViewController.h文件

//

//  ViewController.h

//  block回调

//

//  Created by pengxun523 on 14-4-16.

//  Copyright (c) 2014年 pengxun523. All rights reserved.

//

#import <UIKit/UIKit.h>

@interface ViewController :
UIViewController

@property (weak,
nonatomic) IBOutlet
UIButton *btnOutlet;

- (IBAction)btnClick:(UIButton *)sender;

@end

#import "ViewController.h"

#import "ShowBtnColor.h"

@interface
ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad

{

[super
viewDidLoad];

}

-(void)chargeMyIphone:(void(^)(void))finishBlock

{

}

- (void)didReceiveMemoryWarning

{

[super
didReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

- (IBAction)btnClick:(UIButton *)sender

{

CGRect temp =
CGRectMake(_btnOutlet.frame.origin.x,
_btnOutlet.frame.origin.y,
,
);

[ShowBtnColor
ChangeRootViewBtnRect:temp blockcompletion:^(UIColor *colorEnum) {

/*函数回调
当block运行时就会回到这里*/

_btnOutlet.backgroundColor = colorEnum;

}];

}

@end

ShowBtnColor.h文件

//

//  ShowBtnColor.h

//  block回调

//

//  Created by pengxun523 on 14-4-22.

//  Copyright (c) 2014年 pengxun523. All rights reserved.

//

#import <Foundation/Foundation.h>

typedef
void (^Changcolor)(UIColor *colorEnum);
//定义一个block返回值void參数为颜色值

@interface ShowBtnColor :
NSObject

//回调函数改变btn的颜色值

+ (void)ChangeRootViewBtnRect:(CGRect)rect blockcompletion:(Changcolor)Changcolorblock;

@end

//

//  ShowBtnColor.m

//  block回调

//

//  Created by pengxun523 on 14-4-22.

//  Copyright (c) 2014年 pengxun523. All rights reserved.

//

#import "ShowBtnColor.h"

@implementation ShowBtnColor

+ (void)ChangeRootViewBtnRect:(CGRect)rect blockcompletion:(Changcolor)Changcolorblock

{

UIColor *temp = [UIColor
greenColor];

Changcolorblock(temp);
//运行block

}

@end

执行结果

 当点击button时