百思不得其姐的注意点

框架搭建的注意点

怎样设置cell的左右有间距 ->自定义cell中修改cell的frame

• 重写cell的setFrameL：方法

- (void)setFrame:(CGRect)frame{
    frame.origin.x += 5;
    frame.size.width -= 10;
    frame.size.height -= 1;

    [super setFrame:frame];
}

自定义NavigationController，拦截所有push进来的控制器

• 自定义NavigationController，重写pushViewController:animated:方法

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    if (self.childViewControllers.count > 0) { // 如果push进来的不是第一个控制器
        UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
        [button setTitle:@"返回" forState:UIControlStateNormal];
        [button setImage:[UIImage imageNamed:@"navigationButtonReturn"] forState:UIControlStateNormal];
        [button setImage:[UIImage imageNamed:@"navigationButtonReturnClick"] forState:UIControlStateHighlighted];
        button.size = CGSizeMake(70, 30);
        // 让按钮内部的所有内容左对齐
        button.contentHorizontalAlignment = UIControlContentHorizontalAlignmentLeft;
// [button sizeToFit];
        // 让按钮的内容往左边偏移10
        button.contentEdgeInsets = UIEdgeInsetsMake(0, -10, 0, 0);
        [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];
        [button setTitleColor:[UIColor redColor] forState:UIControlStateHighlighted];
        [button addTarget:self action:@selector(back) forControlEvents:UIControlEventTouchUpInside];

        // 修改导航栏左边的item
        viewController.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:button];

        // 隐藏tabbar
        viewController.hidesBottomBarWhenPushed = YES;
    }

    // 这句super的push要放在后面, 让viewController可以覆盖上面设置的leftBarButtonItem
    [super pushViewController:viewController animated:animated];

}

在自定义的UITabBarController中，通过appearance统一设置所有UITabBarItem的属性

+ (void)initialize
{
    // 通过appearance统一设置所有UITabBarItem的文字属性
    // 后面带有UI_APPEARANCE_SELECTOR的方法, 都可以通过appearance对象来统一设置
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];

    NSMutableDictionary *selectedAttrs = [NSMutableDictionary dictionary];
    selectedAttrs[NSFontAttributeName] = attrs[NSFontAttributeName];
    selectedAttrs[NSForegroundColorAttributeName] = [UIColor darkGrayColor];

    UITabBarItem *item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attrs forState:UIControlStateNormal];
    [item setTitleTextAttributes:selectedAttrs forState:UIControlStateSelected];
}

设置UITabBarItem的图片时，UITabBarItem选中时的图标（selectedImage）对应的图片会被xcode自动渲染成蓝色样式，如何取消图片的自动渲染效果？

vc.tabBarItem.title = title;
vc.tabBarItem.image = [UIImage imageNamed:image];
vc.tabBarItem.selectedImage = [UIImage imageNamed:selectedImage];

如何自定义UITabBarController的UITabBar

• 自定义一个UITabBar
• 在TabBarController中更换tabBar

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 更换tabBar
    [self setValue:[[AHTabBar alloc] init] forKeyPath:@"tabBar"];
}

在自定义的UINavigationController中，通过appearance统一设置UINavigationBar

/** * 当第一次使用这个类的时候会调用一次UINavigationBar的属性 */
+ (void)initialize
{
    // 当导航栏用在AHNavigationController中, appearance设置才会生效
    // UINavigationBar *bar = [UINavigationBar appearanceWhenContainedIn:[self class], nil];
    UINavigationBar *bar = [UINavigationBar appearance];
    [bar setBackgroundImage:[UIImage imageNamed:@"navigationbarBackgroundWhite"] forBarMetrics:UIBarMetricsDefault];
}

如何修改导航栏的内容

• 修改导航栏上的leftBarButtoniItem 和 rightBarButtoniItem可以写一个分类

#import <UIKit/UIKit.h>

@interface UIBarButtonItem (AHExtension)
+ (instancetype)itemWithImage:(NSString *)image highImage:(NSString *)highImage target:(id)target action:(SEL)action;
@end

#import "UIBarButtonItem+AHExtension.h"

@implementation UIBarButtonItem (AHExtension)
+ (instancetype)itemWithImage:(NSString *)image highImage:(NSString *)highImage
target:(id)target action:(SEL)action
{
    UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
    [button setBackgroundImage:[UIImage imageNamed:image] forState:UIControlStateNormal];
    [button setBackgroundImage:[UIImage imageNamed:highImage] forState:UIControlStateHighlighted];
    button.size = button.currentBackgroundImage.size;
    [button addTarget:target action:action forControlEvents:UIControlEventTouchUpInside];
    return [[self alloc] initWithCustomView:button];
}
@end

- (void)viewDidLoad
{
    [super viewDidLoad];

    // 设置导航栏标题
    self.navigationItem.title = @"我的关注";

    // 设置导航栏左边的按钮
    self.navigationItem.leftBarButtonItem = [UIBarButtonItem itemWithImage:@"friendsRecommentIcon" 
    highImage:@"friendsRecommentIcon-click" target:self action:@selector(friendsClick)];

    // 设置背景色
    self.view.backgroundColor = [UIColor blockColor];
}

登录注册界面的注意点

状态栏颜色的更改

/** * 让当前控制器对应的状态栏是白色 */
- (UIStatusBarStyle)preferredStatusBarStyle{
    return UIStatusBarStyleLightContent;
}

修改文本框占位文字的颜色

• 设置文本框的attributedPlaceholder 属性
  
  • @property(nullable, nonatomic,copy) NSAttributedString *attributedPlaceholder
  • NSAttributedString 带有属性的文字

    // 文字属性
    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];

    // NSAttributedString : 带有属性的文字(富文本技术)
    NSAttributedString *placeholder = [[NSAttributedString alloc] initWithString:@"手机号" attributes:attrs];
    self.phoneField.attributedPlaceholder = placeholder;

    NSMutableAttributedString *placehoder = [[NSMutableAttributedString alloc] initWithString:@"手机号"];
    [placehoder setAttributes:@{NSForegroundColorAttributeName : [UIColor whiteColor]} range:NSMakeRange(0, 1)];
    [placehoder setAttributes:@{
                                NSForegroundColorAttributeName : [UIColor yellowColor],
                                NSFontAttributeName : [UIFont systemFontOfSize:30]
                                } range:NSMakeRange(1, 1)];
    [placehoder setAttributes:@{NSForegroundColorAttributeName : [UIColor redColor]} range:NSMakeRange(2, 1)];
    self.phoneField.attributedPlaceholder = placehoder;

• 自定义TextField，重写drawPlaceholderInRect: 方法

- (void)drawPlaceholderInRect:(CGRect)rect
{
    [self.placeholder drawInRect:CGRectMake(0, 10, rect.size.width, 25) withAttributes:@{
                                                 NSForegroundColorAttributeName : [UIColor grayColor],
                                                 NSFontAttributeName : self.font}];
}

• 使用KVC
  
  • 运行时（Runtime）找到_placeholderLabel.textColor，使用KVC更改颜色
    [self setValue:[UIColor grayColor] forKeyPath:@"_placeholderLabel.textColor"];
  • 完整代码实现，自定义一个TextField，实现一下方法

- (void)awakeFromNib{
    // 设置光标颜色和文字颜色一致
    self.tintColor = self.textColor;

    // 不成为第一响应者
    [self resignFirstResponder];
}

/** * 当前文本框聚焦时就会调用 */
- (BOOL)becomeFirstResponder{
    // 修改占位文字颜色
    [self setValue:self.textColor forKeyPath:@"_placeholderLabel.textColor"];
    return [super becomeFirstResponder];
}

/** * 当前文本框失去焦点时就会调用 */
- (BOOL)resignFirstResponder{
    // 修改占位文字颜色
    [self setValue:[UIColor grayColor] forKeyPath:@"_placeholderLabel.textColor"];
    return [super resignFirstResponder];
}

运行时(Runtime)

• 苹果官方一套C语言库
• 能做很多底层操作(比如访问隐藏的一些成员变量\成员方法….)
• 访问成员变量举例

unsigned int count = 0;

// 拷贝出所有的成员变量列表 
//（类似于这样的就是属性@property(nonatomic, strong) UIView *view）
Ivar *ivars = class_copyIvarList([UITextField class], &count);

for (int i = 0; i<count; i++) {
    // 取出成员变量
    // Ivar ivar = *(ivars + i);
    Ivar ivar = ivars[i];

    // 打印成员变量名字
    XMGLog(@"%s", ivar_getName(ivar));
}

// 释放
free(ivars);

// 拷贝出所有的属性列表
unsigned int count = 0;

objc_property_t *properties = class_copyPropertyList([UITextField class], &count);

for (int i = 0; i<count; i++) {
    // 取出属性
    objc_property_t property = properties[i];

    // 打印属性名字， 属性类型
    XMGLog(@"%s <----> %s", property_getName(property), property_getAttributes(property));
}

free(properties);

注册框，登陆框的切换

• 注册框的约束
  
  • 左边约束设置为紧挨着登陆框的右边
  • 顶部约束设置为和登陆框的顶部同高
  • 宽度约束设置为和登录框的约束同高.
• 让控制器拥有登录框左边的约束属性
• 点击按钮时，根据情况更改登录框的左边的约束 的 constant

    // 退出键盘
    [self.view endEditing:YES];

    if (self.loginViewLeftMargin.constant == 0) { // 显示注册界面
        self.loginViewLeftMargin.constant = - self.view.width;
        // 还可以在xib中设置 selected 样式下的文字为已有账号? 
        // 通过设置按钮selected的值，控制按钮的文字
        // button.selected = YES;
        [button setTitle:@"已有账号?" forState:UIControlStateNormal];
    } else { // 显示登录界面
        self.loginViewLeftMargin.constant = 0;
        // button.selected = NO;
        [button setTitle:@"注册账号" forState:UIControlStateNormal];
    }

    [UIView animateWithDuration:0.25 animations:^{
        [self.view layoutIfNeeded];
    }];

推送引导

• 取出当前的版本号，再获得沙盒中存储的版本号
• 当前的版本号不等于沙盒中存储的版本号，自定义一个View作为推送引导界面，添加到window上面
• 存储当前的版本号

NSString *key = @"CFBundleShortVersionString";

// 获得当前软件的版本号
NSString *currentVersion = [NSBundle mainBundle].infoDictionary[key];
// 获得沙盒中存储的版本号
NSString *sanboxVersion = [[NSUserDefaults standardUserDefaults] stringForKey:key];

if (![currentVersion isEqualToString:sanboxVersion]) {
    UIWindow *window = [UIApplication sharedApplication].keyWindow;

    XMGPushGuideView *guideView = [XMGPushGuideView guideView];
    guideView.frame = window.bounds;
    [window addSubview:guideView];

    // 存储版本号
    [[NSUserDefaults standardUserDefaults] setObject:currentVersion forKey:key];
    [[NSUserDefaults standardUserDefaults] synchronize];
}

精华模块

计算两个日期（NSDate）的时间差值

• 基本方法

// 当前时间
NSDate *now = [NSDate date];

// 创建日期格式化类
NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
// 设置日期格式(y:年,M:月,d:日,H:时,m:分,s:秒)
fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
// 发帖时间
NSDate *create = [fmt dateFromString:create_time];

// 当前时间和发帖时间的差值(按秒计算)
NSTimeInterval delta = [now timeIntervalSinceDate:create];

• NSCalendar
  
  • 获得NSDate的每一个元素
  • 比较时间

// 获得NSDate的每一个元素
NSDate *now = [NSDate date];
// 日历
NSCalendar *calendar = [NSCalendar currentCalendar];

// 获得NSDate的每一个元素
NSInteger year = [calendar component:NSCalendarUnitYear fromDate:now];
NSInteger month = [calendar component:NSCalendarUnitMonth fromDate:now];
NSInteger day = [calendar component:NSCalendarUnitDay fromDate:now];
NSDateComponents *cmps = [calendar components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:now];
NSLog(@"%zd %zd %zd", cmps.year, cmps.month, cmps.day);

// 计算两个日期（NSDate）的时间差值

// 日期格式化类
NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
// 设置日期格式(y:年,M:月,d:日,H:时,m:分,s:秒)
fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";

// 当前时间
NSDate *now = [NSDate date];
// 发帖时间
NSDate *create = [fmt dateFromString:create_time];

// 日历
NSCalendar *calendar = [NSCalendar currentCalendar];

// 比较时间
NSCalendarUnit unit = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
NSDateComponents *cmps = [calendar components:unit fromDate:create toDate:now options:0];
NSLog(@"%@ %@", create, now);
NSLog(@"%zd %zd %zd %zd %zd %zd", cmps.year, cmps.month, cmps.day, cmps.hour, cmps.minute, cmps.second);

• 写一个SNDate的分类

#import <Foundation/Foundation.h>

@interface NSDate (AHExtension)
/** * 比较from和self的时间差值 */
- (NSDateComponents *)deltaFrom:(NSDate *)from;

/** * 是否为今年 */
- (BOOL)isThisYear;

/** * 是否为今天 */
- (BOOL)isToday;

/** * 是否为昨天 */
- (BOOL)isYesterday;
@end

#import "NSDate+AHExtension.h"

@implementation NSDate (AHExtension)

- (NSDateComponents *)deltaFrom:(NSDate *)from{
    // 日历
    NSCalendar *calendar = [NSCalendar currentCalendar];

    // 比较时间
    NSCalendarUnit unit = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear | NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    return [calendar components:unit fromDate:from];
}

- (BOOL)isThisYear
{
    // 日历
    NSCalendar *calendar = [NSCalendar currentCalendar];

    NSInteger nowYear = [calendar component:NSCalendarUnitYear fromDate:[NSDate date]];
    NSInteger selfYear = [calendar component:NSCalendarUnitYear fromDate:self];

    return nowYear == selfYear;
}

//- (BOOL)isToday
//{
// // 日历
// NSCalendar *calendar = [NSCalendar currentCalendar];
//
// NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
//
// NSDateComponents *nowCmps = [calendar components:unit fromDate:[NSDate date]];
// NSDateComponents *selfCmps = [calendar components:unit fromDate:self];
//
// return nowCmps.year == selfCmps.year
// && nowCmps.month == selfCmps.month
// && nowCmps.day == selfCmps.day;
//}

- (BOOL)isToday
{
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd";

    NSString *nowString = [fmt stringFromDate:[NSDate date]];
    NSString *selfString = [fmt stringFromDate:self];

    return [nowString isEqualToString:selfString];
}

- (BOOL)isYesterday
{
    // 2014-12-31 23:59:59 -> 2014-12-31
    // 2015-01-01 00:00:01 -> 2015-01-01

    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd";

    NSDate *nowDate = [fmt dateFromString:[fmt stringFromDate:[NSDate date]]];
    NSDate *selfDate = [fmt dateFromString:[fmt stringFromDate:self]];

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *cmps = [calendar components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:selfDate toDate:nowDate options:0];

    return cmps.year == 0
    && cmps.month == 0
    && cmps.day == 1;
}

时间的格式化

• 今年
  
  • 今天
    
    • 一分钟内:刚刚
    • 一小时内：XX分钟前
    • 其他：XX小时前
  • 昨天
    
    • 昨天 19：20：30
  • 其他
    
    • 02-28 19：20：30
• 非今年
  
  • 2015-05-08 18:45:30
    在AHTopic模型中，重写create_time get方法

- (NSString *)create_time{
    // 日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    // 设置日期格式(y:年,M:月,d:日,H:时,m:分,s:秒)
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    // 帖子的创建时间
    NSDate *create = [fmt dateFromString:_create_time];

    if (create.isThisYear) { // 今年
        if (create.isToday) { // 今天
            NSDateComponents *cmps = [[NSDate date] deltaFrom:create];

            if (cmps.hour >= 1) { // 时间差距 >= 1小时
                return [NSString stringWithFormat:@"%zd小时前", cmps.hour];
            } else if (cmps.minute >= 1) { // 1小时 > 时间差距 >= 1分钟
                return [NSString stringWithFormat:@"%zd分钟前", cmps.minute];
            } else { // 1分钟 > 时间差距
                return @"刚刚";
            }
        } else if (create.isYesterday) { // 昨天
            fmt.dateFormat = @"昨天 HH:mm:ss";
            return [fmt stringFromDate:create];
        } else { // 其他
            fmt.dateFormat = @"MM-dd HH:mm:ss";
            return [fmt stringFromDate:create];
        }
    } else { // 非今年
        return _create_time;
    }
}