OC实现简单的点名器

单击视图时，学生姓名随机出现在视图上，再次点击随机停止#import <UIKit/UIKit.h>

@interface MainViewController : UIViewController

@property (nonatomic, assign)NSInteger click;
@property (nonatomic, retain)NSTimer *timer;

@end

#import "MainViewController.h"
#import "NewTimer.h"
@interface MainViewController ()

@end

@implementation MainViewController

- (void)viewDidLoad {
[super viewDidLoad];
_click = 1;
self.view.backgroundColor = [UIColor whiteColor];
UILabel *label= [[UILabel alloc] initWithFrame:CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height)];
label.tag = 1;
label.font = [UIFont systemFontOfSize:100];
label.textColor = [UIColor blackColor];
label.textAlignment = NSTextAlignmentCenter;
label.userInteractionEnabled = YES;
[self.view addSubview:label];
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(clickTap:)];
tap.numberOfTapsRequired = 1;
tap.numberOfTouchesRequired = 1;
[label addGestureRecognizer:tap];
[tap release];
}
- (void)clickTap:(UITapGestureRecognizer *)tap {

if (_click) {
_timer = [NSTimer scheduledTimerWithTimeInterval:0.2 target:self selector:@selector(showTime:) userInfo:nil repeats:YES];
_click = 0;
}
else {
[_timer invalidate];
_click = 1;
}
}
- (void)showTime:(NSTimer *)time {
self.view.backgroundColor = [UIColor colorWithRed:arc4random() % 256 / 255.0 green:arc4random() % 256 / 255.0 blue:arc4random() % 256 / 255.0 alpha:arc4random() % 256 / 255.0];
NSArray *arr = [NSArray arrayWithObjects:@"B", @"A",@"C",@"D",@"E",@"F",nil];
UILabel *label = (UILabel *)[self.view viewWithTag:1];
label.text = [arr objectAtIndex:arc4random() % 6];
}