IOS uses block for chained programming

1. Traditional programming

Method of person

-(void) Eat

{

NSLog (@ "eat");

}

-(void) Learn

{

NSLog (@ "learning");

}

-(void) play

{

NSLog (@ "Entertainment");

}

Do things continuously

Person *p = [[Person alloc] init];

[P eat];

[P learn];

[P play];

2. Chain programming without block

Method of person

-(person *) eat

{

NSLog (@ "eat");

return self;

}

-(person *) Learn

{

NSLog (@ "learning");

return self;

}

-(person *) play

{

NSLog (@ "Entertainment");

return self;

}

To do things in succession, so that they look dizzy

Person *p = [[Person alloc] init];

[[[P eat] learn] play];

3. Chained programming with block

Method of person

-(Person * (^) ()) Eat

{

Return ^{

NSLog (@ "eat");

return self;

};

}

-(Person * (^) ()) Learn

{

Return ^{

NSLog (@ "learning");

return self;

};

}

-(Person * (^) ()) Play

{

Return ^{

NSLog (@ "Entertainment");

return self;

};

}

Do things continuously

Person *p = [[Person alloc] init];

P.eat (). Learn (). Play ();

4. Chained programming with parameters

For example, the way people eat, the parameters are NSString *food

-(Person * (^) ()) Eat: (nsstring*) Food

{

return ^ (food) {

NSLog (@ "eat");

return self;

};

}

If this is the above: P.eat can not be followed: food, because p.eat itself is equivalent to [P EAT: (NSString *) food], if write p.eat:food, equivalent to [P Eat::food], this is wrong.

So the correct wording:

-(Person * (^) (nsstring* food)) eat

{

return ^ (nsstring* food) {

NSLog (@ "eat----%@", food);

return self;

};

}

Do things continuously

P.eat (@ "cabbage"). Learn (). Play ();

5. In summary, the use of block to achieve chain programming is nothing more than: The return value of the method is a block,block inside the actual implementation of the method, block internal return to self; If there are parameters, pass through the parameters of the block.

-(The return value is block) method name

{

Return *{

The block is loaded with code that's really going to execute.

return self;

};

}

IOS uses block for chained programming