获取验证码模型－ios

#import "ViewController.h"@interface ViewController ()@property (nonatomic,strong) UIButton* btn;@property (nonatomic,assign) NSInteger i;@property (nonatomic,strong) NSTimer* timer;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    UIButton* btn = [UIButton buttonWithType:UIButtonTypeCustom];    self.btn = btn;    self.i = 0;    btn.frame = CGRectMake(0, 0, 200, 50);    btn.center = self.view.center;    btn.backgroundColor = [UIColor redColor];    //    [btn setTitle:@"获取验证码" forState:uicontrol];    [btn setTitle:@"获取验证码" forState:UIControlStateNormal];    [btn addTarget:self action:@selector(doAction:) forControlEvents:UIControlEventTouchUpInside];    [self.view addSubview:btn];}-(void)doAction:(UIButton*)btn{    NSTimer* timer = [NSTimer scheduledTimerWithTimeInterval:0.1        target:self selector:@selector(ceshi) userInfo:nil repeats:YES];    self.timer = timer;}-(void)ceshi{    if (self.i <= 0) {        self.i = 60;        [self.timer invalidate];        self.timer = nil;       NSString* title = [NSString stringWithFormat:@"获取验证码"];        [self.btn setTitle:title forState:UIControlStateNormal];    }else{         self.i --;    }    [UIView animateWithDuration:0.1 animations:^{        if (self.i == 60) {             NSString* title = [NSString stringWithFormat:@"获取验证码"];        }else{            NSString* title = [NSString stringWithFormat:@"%ld秒后重新获取",self.i];            [self.btn setTitle:title forState:UIControlStateNormal];        }    }];}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}@end