【代碼筆記】iOS-performSelectorOnMainThread，performselector

【代碼筆記】iOS-performSelectorOnMainThread，performselector

代碼：

RootViewController.h

#import <UIKit/UIKit.h>@interface RootViewController : UIViewController{    UILabel *label;}@end

 

RootViewController.m

- (void)viewDidLoad{    [super viewDidLoad];    // Do any additional setup after loading the view.        self.title=@"performSelectorOnMainThread";    }-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    // performSelectorOnMainThread的作用就如其名，是在主線程執行某個selector， 所有的UIKit裡的調用必須是在主線程的，在非主線程調用會產生非預期的結果也很可能會造成crash,所以當你在其他線程想執行一段UI調用的代碼時，就需要用到這個方法了        [self performSelectorOnMainThread:@selector(loadData) withObject:nil waitUntilDone:NO];    }-(void)loadData{    if (!label) {        label=[[UILabel alloc]init];        label.frame=CGRectMake(50, 80, 200, 200);        label.backgroundColor=[UIColor redColor];        [self.view addSubview:label];    }else    {        [label removeFromSuperview];        label=nil;    }    }