block
- (void)testBlockVariable {
//10,注意outsiderVariable这里是10.，使用的是定义时候的只读拷贝。
NSInteger outsiderVariable = 10;
NSMutableArray *outsideArray = [[NSMutableArray alloc] init];
void (^blockObject)(void) = ^(void){
NSInteger insideVariable = 20;
//30
NSLog(@">member variable = %d", self.memberVariable);
//10
NSLog(@">outside variable = %d",outsiderVariable);
//20
NSLog(@">inside variable = %d",insideVariable);
//这里居然可以变
[outsideArray addObject: @"AddedInsideBlock"];
};
outsiderVariable = 30;
self.memberVariable = 30;
blockObject();
NSLog(@">%d items in outsideArray",[outsideArray count]);
}
-(void)testBlock{
//2-3-3,两个小翅膀，三个小括号，三个void
//1，定义
void (^aBlock) (void) = ^(void){
NSLog(@"hello");
};
aBlock();
//2,变形
void (^bBlock) (void) = 0;
bBlock = ^(void){
NSLog(@"别来无恙啊");
};
bBlock();
//3,数组
void (^CBlock[2]) (void) = {
^(void){
NSLog(@"1");
},
^(void){
NSLog(@"2");
}
};
CBlock[0]();
CBlock[1]();
//4,外部变量，不能改，要改的话加static或者__block
int global = 100;
__block int blockLocal = 100;
static int staticLocal = 100;
void (^dBlock)(void) = ^(void){
NSLog(@">>Sum:%d\n",global + staticLocal);
// global ++;
blockLocal ++;
staticLocal ++;
};
dBlock();
NSLog(@"After modified,global:%d,block local:%d,static local:%d\n",global,blockLocal,staticLocal);
//5, static+const来构成block递归
void (^eBlock)(int) = 0;
static void (^const staticBlock)(int) = ^(int i){
if (i>0) {
NSLog(@">>static %d",i);
staticBlock(i -1 );
}
};
eBlock = staticBlock;
eBlock(5);
//6,__block来构成block递归
__block void(^blockBlock)(int) = 0;
blockBlock = ^(int i){
if (i>0) {
NSLog(@">>block %d",i);
blockBlock(i-1);
}
};
blockBlock(5);
//dispatch_semaphore_t来实现queue之间通讯。
//task2必须等待task1执行完毕，主线程必须等待task2执行完毕。
int length =10;
int data[length];
for (int i=0; i<length; i++) {
data[i] = i;
}
__block int *pArray = data;
//创建semaphore。
__block dispatch_semaphore_t sem1 = dispatch_semaphore_create(0);
__block dispatch_semaphore_t sem2 = dispatch_semaphore_create(0);
dispatch_queue_t queue = dispatch_queue_create("StudyBlocks", NULL);
__block int s=0;
dispatch_block_t task1 = ^(void){
int sum = 0;
for (int i=0; i<length ; i++) {
sum += pArray[i];
//sleep(1000);
}
s = sum;
NSLog(@">>Sum:%d",sum);
//发送一个semaphore
dispatch_semaphore_signal(sem1);
};
dispatch_block_t task2 = ^(void){
dispatch_semaphore_wait(sem1, DISPATCH_TIME_FOREVER);
int sum = s;
for (int i = 0; i<length; i++) {
sum-= pArray[i];
}
s = sum;
NSLog(@">>after subtract:%d",sum);
dispatch_semaphore_signal(sem2);
};
dispatch_async(queue, task1);
dispatch_async(queue, task2);
//等待一个semophore
dispatch_semaphore_wait(sem2, DISPATCH_TIME_FOREVER);
NSLog(@"-------------");
//灭掉这个semaphore
//dispatch_release(sem);
//dispatch_release(queue);
//7，dispatch_apply实现并行求和
dispatch_queue_t queueApply = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
__block int sum = 0;
dispatch_apply(length,queueApply, ^(size_t i) {
sum+=pArray[i];
});
NSLog(@">>sum:%d",sum);
//dispatch_release(queueApply);
//8，dispatch_group_t来插一脚
__block int sum8 = 0;
__block dispatch_semaphore_t taskSem8 = dispatch_semaphore_create(0);
dispatch_queue_t queue8 = dispatch_queue_create("StudyBlocks8", NULL);
dispatch_group_t group8 = dispatch_group_create();
dispatch_block_t task18 = ^(void){
int s = 0;
for (int i= 0; i<length; i++) {
s+= pArray[i];
}
sum8 = s;
NSLog(@">>after add:%d",sum);
dispatch_semaphore_signal(taskSem8);
};
dispatch_block_t task28 = ^(void){
dispatch_semaphore_wait(taskSem8, DISPATCH_TIME_FOREVER);
int s = sum8;
for (int i=0; i<length; i++) {
s-= pArray[i];
}
sum8 = s;
NSLog(@">>after substract : %d",sum8);
};
dispatch_group_async(group8, queue8, task18);
dispatch_group_async(group8, queue8, task28);
dispatch_group_wait(group8, DISPATCH_TIME_FOREVER);
}