cancelPreviousPerformRequestsWithTarget

来源：互联网发布：树莓派 ubuntu mate 编辑：程序博客网时间：2024/06/14 17:59

from stackoverflow: http://stackoverflow.com/questions/7589644/why-doesnt-cancelpreviousrequestswithtarget-cancel-an-nstimer

#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad{    [super viewDidLoad];    UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];    [button setFrame:CGRectMake(20, 20, 280, 30)];    [button setTitle:@"button" forState:UIControlStateNormal];    [button addTarget:self action:@selector(buttonClick:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:button];        // [NSTimer scheduledTimerWithTimeInterval:5.0f target:self selector:@selector(buttonClick:) userInfo:nil repeats:NO];    [self performSelector:@selector(buttonClick:) withObject:@"Hello" afterDelay:6.0f];    // withObject:的参数应该和cancelPreviousPerformRequestsWithTarget:selector:object:的object:参数相同，这个参数可以填为nil}- (void)buttonClick:(id)sender{    [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(buttonClick:) object:@"Hello"];    // [NSObject cancelPreviousPerformRequestsWithTarget:self];    // use this method cancel NSTimer is invalid    static int i = 0;    NSLog(@"%d", i++);}@end