Block I know

In this article, refer to the video from instructor Yan Jie.

 

When using block, you must declare and instantiate the block first.

 

BLOCK statement:

Block is divided into several situations: return values, parameters, no return values, no return values, and no parameters

INT (^ argreturnblock) (INT, INT) with return values and parameters );

 

The other types are int (^ returnblock )();

Void (argblock) (INT, INT );

Void (nonblock )();

 

Then instantiate

 

For example:

INT (INT argreturnblock) (INT, INT );

Argreturnblock = ^ (INT V1, int V2 ){

Return V1 + V2;

};

 

Finally, call

 

Int result = argreturnblock (13, 34 );

 

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Example of block callback;

Whether the listener button has been clicked

Mybutton * BTN = [[mybutton alloc] init]; BTN. buttonblock = ^ (mybutton * testbtn) {nslog (@ "% @ ___ the store", testbtn) ;}; [BTN click];

When the click method is called, it will be called back to the block method above.

#import <Foundation/Foundation.h>@class MyButton;typedef void(^listenBlock)(MyButton *sender);@interface MyButton : NSObject@property (nonatomic,assign) listenBlock buttonBlock;- (void)click;@end

In

#import "MyButton.h"@implementation MyButton- (void)click{    _buttonBlock(self);}@end

 

When the click method is called,

Will jump to the click method in mybutton. M, which contains _ buttonblock (Self );

It will jump to the place where the _ buttonblock declaration is made, that is, the place where the block is instantiated outside.

 

Block usage:

 

• Callback processing when the task is completed
• Message listener callback Processing
• Error callback Processing
• Enumeration callback
• View animation and Transformation
• Sort
• Http://blog.csdn.net/jasonblog/article/details/7756763
• For details, refer to the content in this link.

 

How to store blocks,

 

Block I know