Objective-c-code blocks block

Block blocks of code

/* What the block wants to know 1> how to define the block variable int (^sumblock) (int, int), void (^myblock) (), 2> How to use block encapsulation code ^ (int a, int b) { return a-B; }; ^ () {NSLog (@ "----------");}; ^ {NSLog (@ "----------");};　3> block Access outside variable * block inside can access the outside of the variable * By default, the inside block cannot modify the outside local variable * to the local variable plus the __block keyword, this local variable can be modified within the block 4> Use typedef to define the block type typedef int (^myblock) (int, int); You can then use this type of Myblock to define the block variable Myblock block; Myblock B1, B2; B1 = ^ (int A, int.) {return a-B;}; Myblock B3 = ^ (int A, int.) {return a-B;}; */typedef int(*sump) (int,int);typedef int(^myblock) (int,int);intSumintAintb) {returnA + b;}intMain () {//Int (*p) (int, int) = SUM;    //Int (*P2) (int, int) = SUM;    //Sump p = sum;    //sump p2 = sum;    / * INT (^sumblock) (int, int);    Sumblock = ^ (int a, int b) {return a + B;    };    Int (^minusblock) (int, int) = ^ (int A, int.) {return a-B; };*/Myblock Sumblock; Sumblock = ^ (intAintb) {returnA + b;    }; Myblock Minusblock = ^ (intAintb) {returnA-B;    }; Myblock Multiplyblock = ^ (intAintb) {returnA * b; };NSLog(@"%d-%d-%d", Multiplyblock (2,4), Sumblock (Ten,9), Minusblock (Ten,8));return 0;}voidTest3 () {intA =Ten; __blockintb = -;void(^block)    (); block = ^{//block internal access to external variables        //nslog (@ "a =%d", a);        //By default, the outer local variables cannot be modified inside the block        //a =;        //To add the __block keyword to the local variable, this local variable can be modified within the blockb = -;    }; Block ();}//block with return value, tangible parametervoidTest2 () {/*//pointer function pointer Int (*P) (int, int) = SUM;     int d = P (10, 12);     NSLog (@ "%d", d); */    int(^sumblock) (int,int) = ^(intAintb) {returnA + b; };intc = Sumblock (Ten, One);//Use a block to output n horizontal lines    void(^lineblock) (int) =  ^(intN) { for(inti =0; i<n; i++) {NSLog(@"----------------");    }    }; Lineblock (5);}//No return value, block with no formal parametersvoidTest () {//block to save a piece of code    //block flag: ^    /* block is similar to the function: 1. You can save code 2. There is a return value of 3. Physical Parameters 4. Call the same way * /    //define block variables    / * void (^myblock) () = ^ () {NSLog (@ "----------------");    NSLog (@ "----------------"); };*/    //If the block has no formal parameters, you can omit the following ()    void(^myblock) () = ^{NSLog(@"----------------");NSLog(@"----------------"); };//Use block variable to invoke code inside blockMyblock (); Myblock ();}

Objective-c-code blocks block