目录

1. 用GCD的方式来实现单例
2. TabBar的图片显示原始样貌而非变为默认的蓝色- (UIImage *)imageWithRenderingMode:(UIImageRenderingMode)renderingMode
3. 设置导航的标题
4. 计算时间差
5. 原价上的删除线(较为直接粗暴的方法)
6. 停靠模式
7. 去掉cell间的分隔线
8. 快速创建视图控制器
9. 使用if判断增强程序的鲁棒性

用GCD的方式来实现单例

+ (DownloadManager *)sharedInstance
{
    static DownloadManager *manager = nil;
    
    static dispatch_once_t onceToken;
    
    dispatch_once(&onceToken, ^{
        manager = [[DownloadManager alloc] init];
    });
    
    return manager;
}

TabBar的图片显示原始样貌而非变为默认的蓝色- (UIImage *)imageWithRenderingMode:(UIImageRenderingMode)renderingMode

   ctrl.tabBarItem.image = [[UIImage imageNamed:imageArray[i]] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

设置导航的标题

self.navigationItem.titleView = <#UIView#>;

计算时间差

NSDateFormatter *df = [[NSDateFormatter alloc] init];
[df setDateFormat:@"yyyy-MM-dd HH:mm:ss"];

NSString *dateStr = [model.expireDatetime substringToIndex:model.expireDatetime.length - 2];
NSDate *releaseDate = [df dateFromString:dateStr];

NSCalendar *calendar = [NSCalendar currentCalendar];

/* 
 计算时间差
 第一个参数:年月日时分秒
 第二个参数:开始时间
 第三个参数:结束时间
 第四个参数:选项(传0就可以)
 */
unsigned int unit = NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
NSDateComponents *dateComponents = [calendar components:unit fromDate:[NSDate date] toDate:releaseDate options:0];

self.timeLabel.text = [NSString stringWithFormat:@"%02ld:%02ld:%02ld", dateComponents.hour, dateComponents.minute, dateComponents.second];

原价上的删除线(较为直接粗暴的方法)

CGFloat width = [priceStr boundingRectWithSize:CGSizeMake(300, 20) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:17]} context:nil].size.width;
                                                                                                                        
// 画横线
UIView *lineView = [[UIView alloc] initWithFrame:CGRectMake(0, 10, width, 1)];
lineView.backgroundColor = [UIColor blackColor];
[self.priceLabel addSubview:lineView];  

停靠模式

starImageView.contentMode = UIViewContentModeLeft;
starImageView.clipsToBounds = YES;

去掉cell间的分隔线

_tbView.separatorStyle = UITableViewCellSeparatorStyleNone;

快速创建视图控制器

// 视图控制器数组
NSArray *ctrlArray = @[@"LimitFreeViewController", @"ReduceViewController", @"FreeViewController", @"SubjectViewController", @"RankViewController"];  

// 循环创建视图控制器
NSMutableArray *array = [NSMutableArray array];

for (int i = 0; i < ctrlArray.count; i++) {
    
    // 视图控制器
    Class cls = NSClassFromString(ctrlArray[i]);
    UIViewController *ctrl = [[cls alloc] init];  

    // 创建导航
    UINavigationController *navCtrl = [[UINavigationController alloc] initWithRootViewController:ctrl];
    
    [array addObject:navCtrl];
}
// 给tabBarCtrl的管理视图控制器属性赋值
self.viewControllers = array;  

使用if判断增强程序的鲁棒性

+ (UILabel *)createLabelWithFrame:(CGRect)frame title:(NSString *)title textColor:(UIColor *)color font:(UIFont *)font textAlignment:(NSTextAlignment)textAlignment numberOfLines:(NSInteger)numberOfLines
{
    UILabel *label = [[UILabel alloc] initWithFrame:frame];
#warning if
    if (title) {
        label.text = title;
    }
    if (color) {
        label.textColor = color;
    }
    …………………………………………        
    
    return label;
}