异步处理1

在新线程中执行处理:

问题:应用需要执行非常耗时的任务,但是又希望用户界面保持响应,不会受到新操作的影响.

• 不开辟一个新线程的做法

#import "ViewController.h"
@interface ViewController ()
@property(nonatomic,strong)UIActivityIndicatorView*myActivityIndicator;
@property(nonatomic,strong)UIButton*myButton;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
   
//    创建button
    self.myButton=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    self.myButton.frame=CGRectMake(20, 403, 280, 37);
    
    [self.myButton addTarget:self action:@selector(bigTaskAction) forControlEvents:UIControlEventTouchUpInside];
    
    [self.myButton setTitle:@"do long task" forState:UIControlStateNormal];

    [self.view addSubview:_myButton];
    
    //创建indicator
    self.myActivityIndicator=[[UIActivityIndicatorView alloc]init];
    self.myActivityIndicator.frame=CGRectMake(142, 211, 37, 37);
    
    self.myActivityIndicator.activityIndicatorViewStyle=UIActivityIndicatorViewStyleWhiteLarge ;
    
    self.myActivityIndicator.hidesWhenStopped=NO;
    
    [self.view addSubview:self.myActivityIndicator];
    
}
-(void)bigTask{
    @autoreleasepool {
        for (int i=0; i<10000; i++) {
            NSString*newString=[NSString stringWithFormat:@"i=%d",i];
            NSLog(@"%@ ",newString);
        }
        [self.myActivityIndicator stopAnimating];
    }
}

//没有开辟新线程
-(void)bigTaskAction{
    [self.myActivityIndicator startAnimating];
    [self bigTask];
   
    
}

@end

• 开辟一个新线程

-(void)bigTaskAction{
    [self.myActivityIndicator startAnimating];
//开辟新的线程
   [NSThread detachNewThreadSelector:@selector(bigTask) toTarget:self withObject:nil];
}

总结:

一般情况下执行代码的时候,是一行一行的执行,上一行没有执行完成会等待,现在进行开辟线程,可同时执行 这里就是: 一边for循环在处理 ,一边指示器在界面上响应