IOS开发基础知识--碎片15

1:将自定义对象转化成NsData存入数据库

要转为nsdata自定义对象要遵循<NSCoding>的协议,然后实现encodeWithCoder，initwithcode对属性转化,实例如下:

HMShop.h
#import <Foundation/Foundation.h>

@interface HMShop : NSObject <NSCoding>
@property (nonatomic, copy) NSString *name;
@property (nonatomic, assign) double  price;
@end

HMShop.m
#import "HMShop.h"

@implementation HMShop
- (void)encodeWithCoder:(NSCoder *)encoder
{
    [encoder encodeObject:self.name forKey:@"name"];
    [encoder encodeDouble:self.price forKey:@"price"];
}

- (id)initWithCoder:(NSCoder *)decoder
{
    if (self = [super init]) {
        self.name = [decoder decodeObjectForKey:@"name"];
        self.price = [decoder decodeDoubleForKey:@"price"];
    }
    return self;
}

- (NSString *)description
{
    return [NSString stringWithFormat:@"%@ <-> %f", self.name, self.price];
}
@end

操作:

- (void)addShops
{
    NSMutableArray *shops = [NSMutableArray array];
    for (int i = 0; i<100; i++) {
        HMShop *shop = [[HMShop alloc] init];
        shop.name = [NSString stringWithFormat:@"商品--%d", i];
        shop.price = arc4random() % 10000;
        
        NSData *data = [NSKeyedArchiver archivedDataWithRootObject:shop];
        [self.db executeUpdateWithFormat:@"INSERT INTO t_shop(shop) VALUES (%@);", data];
    }
}

- (void)readShops
{
    FMResultSet *set = [self.db executeQuery:@"SELECT * FROM t_shop LIMIT 10,10;"];
    while (set.next) {
        NSData *data = [set objectForColumnName:@"shop"];
        HMShop *shop = [NSKeyedUnarchiver unarchiveObjectWithData:data];
        NSLog(@"%@", shop);
    }
}

＊把对象转成nsdata的理由，因为在存入数据库时会变成字符串，不利转化，所以先把其序列化转化成nsdata，然后存进数据库，取出时同样先为nsdata再转化；

2:增加子控制器，用来提取一些公共的内容布局，瘦身当前viewcontroller

DetailsViewController *details = [[DetailsViewController alloc] init];
    details.photo = self.photo;
    details.delegate = self;
    [self addChildViewController:details]; 
    CGRect frame = self.view.bounds;
    frame.origin.y = 110;
    details.view.frame = frame;
    [self.view addSubview:details.view];
    [details didMoveToParentViewController:self];

3:用协议来分离出调用

在子控制器创建一个协议，然后在其内部对它进行处理传参

子控制器.h
@protocol DetailsViewControllerDelegate

- (void)didSelectPhotoAttributeWithKey:(NSString *)key;

@end


@interface DetailsViewController : UITableViewController

@property (nonatomic, strong) Photo *photo;
@property (nonatomic, weak) id <DetailsViewControllerDelegate> delegate;

@end

子控制器.m

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *key = self.keys[(NSUInteger) indexPath.row];
    //对它进行传参，让其在父控制器去实现
    [self.delegate didSelectPhotoAttributeWithKey:key]; 
}


父控制器.m
@interface PhotoViewController () <DetailsViewControllerDelegate>
@end

然后(得到参数，进行原本子控制器要进行的操作)：
- (void)didSelectPhotoAttributeWithKey:(NSString *)key
{
    DetailViewController *detailViewController = [[DetailViewController alloc] init];
    detailViewController.key = key;
    [self.navigationController pushViewController:detailViewController animated:YES];
}

4:关于kvo的运用

//进度值改变 增加kvo 传值 key为fractionCompleted
- (void)setProgress:(NSProgress *)progress{
    if (_progress) {
        [_progress removeObserver:self forKeyPath:@"fractionCompleted"];
    }
    _progress = progress;
    if (_progress) {
        [_progress addObserver:self forKeyPath:@"fractionCompleted" options:NSKeyValueObservingOptionNew context:nil];
    }
}
//消息kvo消息
- (void)dealloc{
    if (_progress) {
        [_progress removeObserver:self forKeyPath:@"fractionCompleted"];
    }
    _progress = nil;
}

#pragma mark KVO
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
    if ([keyPath isEqualToString:@"fractionCompleted"]) {
        NSProgress *progress = (NSProgress *)object;
        NSProgress *cellProgress = _offsourecebean.cDownloadTask.progress;
        BOOL belongSelf = NO;
        if (cellProgress && cellProgress == progress) {
            belongSelf = YES;
        }
        dispatch_async(dispatch_get_main_queue(), ^{
            if (self) {
                [self showProgress:progress belongSelf:belongSelf];
            }
        });
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

＊注意增加监听后在不用时要进行消除，移除观察，其中addObserver可以是其它对象，然后在其内部实现observeValueForKeyPath这个协议；增加监听时可以设置options类型，也可以多类型一起；比如NSKeyValueObservingOptionNew|NSKeyValueObservingOptionOld;当被监听的对象发生变化时，会马上通知监听对象，使它可以做出一些响应，比如视图的更新；

 5:自定义UITableViewCell的accessoryView 判断哪个Button按下

UITableview的开发中经常要自定义Cell右侧的AccessoryView，把他换成带图片的按钮，并在用户Tap时判断出是哪个自定义按钮被按下了。

创建自定义按钮，并设为AccessoryView
if (cell == nil) { 
    cell = [[UITableView alloc] initWithStyle:UITableViewCellStyleDefault                                  reuseIdentifier:identifier]; 
   
    UIImage *image= [ UIImage imageNamed:@"delete.png" ];
    UIButton *button = [ UIButton buttonWithType:UIButtonTypeCustom ];
    CGRect frame = CGRectMake( 0.0 , 0.0 , image.size.width , image.size.height );
    button. frame = frame;
    [button setBackgroundImage:image forState:UIControlStateNormal ];
    button. backgroundColor = [UIColor clearColor ];
    [button addTarget:self action:@selector(buttonPressedAction  forControlEvents:UIControlEventTouchUpInside]; 
    cell. accessoryView = button;
 } 

如果将Button加入到cell.contentView中，也是可以的。
cell.contentView addSubview:button];

在Tap时进行判断，得到用户Tap的Cell的IndexPath
- (void)buttonPressedAction  id)sender 
{ 
   UIButton *button = (UIButton *)sender; 
   (UITableViewCell*)cell = [button superview]; 
   int row = [myTable indexPathForCell:cell].row; 
} 

对于加到contentview里的Button
(UITableViewCell*)cell = [[button superview] superview];

6:直接运用系统自带的UITableViewCell，其中cell.accessoryView可以自定义控件

#import "MyselfViewController.h"

@interface MyselfViewController ()

@property (nonatomic, retain) NSMutableArray *datasource;

@end

@implementation MyselfViewController
-(void)dealloc {
    [_datasource release];
    [super dealloc];
}

-(NSMutableArray *)datasource {
    if (!_datasource) {
        self.datasource = [NSMutableArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"MyselfList" ofType:@"plist"]];
    }
    return _datasource;
}

-(instancetype)init {
    self = [super initWithStyle:UITableViewStyleGrouped];
    if (self) {

    }
    return self;
}



- (void)viewDidLoad {
    [super viewDidLoad];

    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:@"cell"];
    self.tableView.rowHeight = 70;
    self.navigationItem.title = @"我的";
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
    return self.datasource.count;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

    // Return the number of rows in the section.
    return [self.datasource[section] count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"cell" forIndexPath:indexPath];
    NSDictionary *dict = [self.datasource[indexPath.section] objectAtIndex:indexPath.row];
    cell.textLabel.text = dict[@"title"];
    cell.imageView.image = [UIImage imageNamed:dict[@"imageName"]];

    if (indexPath.section == 2 && indexPath.row == 0) {
        cell.accessoryView = [[[UISwitch alloc] init] autorelease];
    } else {
        cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    }
    
    return cell;
}

@end