一、多線程的概念
線程就是指每個獨立運行的代碼片;
每個賑災運行的程序(即進程),至少包含一個線程,這個線程爲主線程。
只有一個主線程的程序,稱爲單線程程序。
擁有多個線程的程序,稱爲多線程程序。
多個線程可以併發執行。
注意:
iOS中關於UI的添加和刷新必須在主線程中操作。
iOS中多線程的種類有四種:
NSThread
NSOperationQueue(是隊列,沒有開闢線程的能力)
NSObject
GCD
二、NSThread
demo:
-(void)tesr{
UIImageView* imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"1.jpg"]];
[self.view addSubview:imageView];
//輕量級的多線程調用方法,當使用alloc init的方式,需要手動啓動,便利構造器的方式不需要手動啓動
//object,是線程回調方法的參數,如果不需要參數,直接賦予值爲nil;
NSThread* forThread = [[NSThread alloc]initWithTarget:self selector:@selector(forMethod) object:nil];
forThread.name = @"我是老二";
//線程優先級,0到1.0
forThread.threadPriority = 1.0;
//啓動線程
[forThread start];
//得到當前線程的信息
NSLog(@"imageThread---%@",[NSThread currentThread]);
NSMutableArray* array = [NSMutableArray array];
for (int j = 1; j<11; j++) {
UIImage * item = [UIImage imageNamed:[NSString stringWithFormat:@"%d.jpg",j]];
[array addObject:item];
}
imageView.animationImages = array;
imageView.animationDuration = 2.0;
// imageView.animationRepeatCount = 10;
//啓動動畫
[imageView startAnimating];
}
//循環一億次
-(void)forMethod{
NSLog(@"forThread---%@",[NSThread currentThread]);
for(int i = 0;i<1000000;i++){
NSLog(@"%d",i);
}
}
效果就是可以看到動圖的加載並不受循環的影響,這就是線程的意義。
demo:
記住線程如果是我們自己開闢的,那麼即使在mrc模式下,也需要將其放入自動釋放池中。
//nsthread學習
-(void)threadStudy{
//便利構造器的方式,五返回值
[NSThread detachNewThreadSelector:@selector(thread_1Action:) toTarget:self withObject:@"thread_1"];
//通過alloc的方式創建
NSThread *thread_2 = [[NSThread alloc]initWithTarget:self selector:@selector(thread_2Action:) object:@"thread_2"];
[thread_2 start];
thread_2.name = @"最優先";
thread_2.threadPriority = 1.0;
[NSThread detachNewThreadSelector:@selector(thread_3Action:) toTarget:self withObject:@"thread_3"];
}
-(void)thread_1Action:(NSString*)string{
//當子線程是我們手動開闢的,那麼就需要我們自己管理內存
@autoreleasepool {
NSLog(@"%@",[NSThread currentThread]);
NSLog(@"%@",string);
}
}
-(void)thread_2Action:(NSString*)string{
@autoreleasepool {
NSLog(@"%@",[NSThread currentThread]);
NSLog(@"%@",string);
}
}
-(void)thread_3Action:(NSString*)string{
@autoreleasepool {
NSLog(@"%@",[NSThread currentThread]);
NSLog(@"%@",string);
}
}
記住線程如果是我們自己開闢的,那麼即使在mrc模式下,也需要將其放入自動釋放池中。
三、NSObject
//NSObject的多線程方式
// 1.從主線程進入子線程
[self performSelectorInBackground:@selector(objectAction:) withObject:@"090987開闢子線程的方式"];
在objectAction方法中,寫代碼並回到主線程:
-(void)objectAction:(NSString*)string{
NSLog(@"參數%@",string);
//從子線程中回到主線程
/**
* Description
*
* @param BOOL yes:只有回主線程的回調方法執行結束才執行下面的操作。NO:與之相反
*
* @return 沒有返回值
*/
[self performSelectorOnMainThread:@selector(backMainAction) withObject:nil waitUntilDone:NO];
NSLog(@"我是在回主線程的底下打印的");
}
四、GCD
demo:
//串行隊列,一次只執行一個任務
-(void)serialQueue{
//創建串行隊列
/**
* Description
*
* @param label#> 當前隊列的標籤 description#>
* @param attr#> 字符 description#>
*
* @return 返回一個dispatch_queue_t
*/
dispatch_queue_t serialQueue = dispatch_queue_create("串行隊列",DISPATCH_QUEUE_SERIAL);
//爲串行隊列添加任務
dispatch_async(serialQueue, ^{
NSLog(@"你好------%@",[NSThread currentThread]);
});
//異步任務
dispatch_async_f(serialQueue, "建華會說話了", function);
dispatch_async(serialQueue, ^{
NSLog(@"會上學了%@",[NSThread currentThread]);
});
dispatch_async(serialQueue, ^{
NSLog(@"結婚了%@",[NSThread currentThread]);
});
dispatch_async(serialQueue, ^{
NSLog(@"被全退了%@",[NSThread currentThread]);
});
dispatch_async(serialQueue, ^{
NSLog(@"墮落了%@",[NSThread currentThread]);
});
dispatch_async(serialQueue, ^{
NSLog(@"洗心革面了%@",[NSThread currentThread]);
});
dispatch_async(serialQueue, ^{
NSLog(@"出家了%@",[NSThread currentThread]);
});
NSLog(@"我在最下面你%@",[NSThread currentThread]);
}
//定義一個回調函數
void function(void* str){
printf("%s\n",str);
}
//創建並行隊列
-(void)concurrentQueue{
//創建並行隊列
dispatch_queue_t concurrentQueue = dispatch_queue_create("並行隊列", DISPATCH_QUEUE_CONCURRENT);
//同步任務所處的線程就是當前線程
dispatch_async(concurrentQueue, ^{
NSLog(@"你好------%@",[NSThread currentThread]);
});
//異步任務
dispatch_async_f(concurrentQueue, "建華會說話了", function);
dispatch_async(concurrentQueue, ^{
NSLog(@"會上學了%@",[NSThread currentThread]);
});
dispatch_async(concurrentQueue, ^{
NSLog(@"結婚了%@",[NSThread currentThread]);
});
dispatch_async(concurrentQueue, ^{
NSLog(@"被全退了%@",[NSThread currentThread]);
});
dispatch_async(concurrentQueue, ^{
NSLog(@"墮落了%@",[NSThread currentThread]);
});
dispatch_async(concurrentQueue, ^{
NSLog(@"洗心革面了%@",[NSThread currentThread]);
});
dispatch_async(concurrentQueue, ^{
NSLog(@"出家了%@",[NSThread currentThread]);
});
}
//系統提供的隊列,全局隊列
-(void)globalQueue{
//系統提供的一個全局隊列
//參數一,權限,即優先級 2,0 ,-2,INT16_MIN。參數二,系統預留
dispatch_queue_t globalQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
//添加任務
//全局隊列是一個系統提供的並行隊列
dispatch_async(globalQueue, ^{
NSLog(@"*******--------------%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"*******------36736735736737%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"*******-37373756473637635%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"******6666666666666666%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"****555555555555555%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"*******------%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"*******----%@",[NSThread currentThread]);
});
dispatch_async(globalQueue, ^{
NSLog(@"*******%@",[NSThread currentThread]);
});
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
//gcd常見的使用方式,全局隊列和主隊列結合使用
-(void)globalAndMainQueue{
dispatch_async(dispatch_get_global_queue(0, 0), ^{
//在全局隊列裏執行耗時的操作,因爲全局隊列執行的任務是在子線程中,不會阻塞主線程
dispatch_async(dispatch_get_main_queue(), ^{
//該block中所執行的任務是在主隊列中執行,那麼該任務是在主線程中執行,在此處進行刷新UI的行爲。
});
});
}
//gcd中讓某些代碼執行一次
-(void)onceToken{
static UIImage* image = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
//此處的代碼只執行一次
image = [[UIImage alloc]init];
});
}
//其他的方法
-(void)otherGCD{
//延時執行的
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
NSLog(@"五秒真男人");
});
//重複執行
dispatch_apply(3, dispatch_get_global_queue(0,0), ^(size_t size) {
NSLog(@"五秒再來一次");
});
}
五、隊列
demo:
//invocation的回調方法
-(void)invocationAction{
//打印當前的線程
NSLog(@"%@-------判斷是否爲主線程%d",[NSThread currentThread],[[NSThread currentThread] isMainThread]);
}
//operation和operationQueue
-(void)operationQueue{
//初始化一個任務target - action operation並沒有開闢線程,將operation在那個線程中使用,operation所在的線程就是當前線程。
NSInvocationOperation* invocation = [[NSInvocationOperation alloc]initWithTarget:self selector:@selector(invocationAction) object:nil];
//當加入隊列的時候,不需要手動啓動,在隊列則不用手動啓動
[invocation start];
//操作的block的方式
NSBlockOperation* blockOperation = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@------",[NSThread currentThread]);
}];
//添加多個block操作,當使用addExecutionBlock爲BlockOPeration添加可執行的block的時候,這些可執行的block會在當前線程,或者其他子線程中進行。
//在啓動之前添加事件
for (int i=0; i<10; i++) {
[blockOperation addExecutionBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],i);
}];
};
blockOperation.completionBlock = ^(){
NSLog(@"我就是最後一個,你們隨便折騰");
};
//啓動操作
[blockOperation start];
NSLog(@"我是在最底下");
}
//queue的學習,隊列 nsoperationQuene 是對gcd的一個oc級別的封裝。
-(void)operationOperationQuene{
//先初始化隊列對象,(其他隊列:除了主隊列,自己初始化的隊列都是其他隊列)
NSOperationQueue *otherQueue = [[NSOperationQueue alloc]init];
//隊列的最大併發數,在同一時刻最多可執行的操作
// otherQueue.maxConcurrentOperationCount = 1;
//創建可執行的操作對象
/*for (int i=0; i<10; i++) {
NSBlockOperation* blockopeartion = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],i);
}];
//將block操作添加到隊列中去
[otherQueue addOperation:blockopeartion];
};*/
NSBlockOperation* blockopeartion_0 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],0);
}];
NSBlockOperation* blockopeartion_1 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],1);
}];
NSBlockOperation* blockopeartion_2 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],2);
}];
NSBlockOperation* blockopeartion_3 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],3);
}];
NSBlockOperation* blockopeartion_4 = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],4);
}];
//爲時間添加依賴關係,先添加依賴,在添加事件到隊列中
[blockopeartion_4 addDependency:blockopeartion_3];
//當操作對象添加到隊列中之後,就不需要手動啓動了
[otherQueue addOperation:blockopeartion_0];
[otherQueue addOperation:blockopeartion_1];
[otherQueue addOperation:blockopeartion_2];
[otherQueue addOperation:blockopeartion_3];
[otherQueue addOperation:blockopeartion_4];
}
//主隊列
-(void)mainQueue{
NSLog(@"%@",[NSThread currentThread]);
//先創建主隊列的對象
NSOperationQueue* mainQueue = [NSOperationQueue mainQueue];
for (int i = 0 ; i < 10 ; i ++) {
NSBlockOperation* blockOperation = [NSBlockOperation blockOperationWithBlock:^{
NSLog(@"%@-----%d",[NSThread currentThread],i);
}];
[mainQueue addOperation:blockOperation];
}
}