拋出異常

NSException* ex = [NSException exceptionWithName:@"name" reason:@"reason" userInfo:nil];
[ex raise];

UILabel文字添加刪除線

    NSAttributedString* attrStr =
        [[NSAttributedString alloc] initWithString:@"ddddd"
                                        attributes:
                                            @{ NSFontAttributeName : [UIFont systemFontOfSize:20.f],
                                                NSForegroundColorAttributeName : [UIColor redColor],
                                                NSStrikethroughStyleAttributeName : @(NSUnderlineStyleSingle | NSUnderlinePatternSolid),
                                                NSStrikethroughColorAttributeName : [UIColor blueColor] }];
    self.label.attributedText = [attrStr copy];

自定義控件的數據源設置

自定義控件應該自己定義相關的數據源，
然后其他數據源想要使用這個自定義控件，
就把自定義控件的模型放到數據源模型中，
然后通過setValue ：forKey ：來進行對自定義控件的模型賦值。

NSString

//去掉空格
NSString* _titleLabelOutSpace = [text stringByReplacingOccurrencesOfString:@" " withString:@""];
//NSString －>NSInteger
[_titleLabelOutSpace integerValue];

NSArray

//NSString  NSArray  互轉
NSArray *arr = [@"a,b,c" componentsSeparatedByString:@","];


- (void)hasString:(NSString*)str1 string2:(NSString*)str2
{
    NSString* string1 = str1;
    NSString* string2 = str2;
    NSRange range = [string1 rangeOfString:string2];
    NSUInteger location = range.location;
    NSUInteger length = range.length;
    NSString* astring = [[NSString alloc] initWithString:[NSString stringWithFormat:@"Location:%zd,Leight:%zd", location, length]];
    NSLog(@"astring:%@", astring);
}
    [self hasString:@"1111111" string2:@"2"];
   //astring:Location:9223372036854775807, length:0
    [self hasString:@"11111112" string2:@"2"];
   //astring:Location:8,Leight:1
可以根據length來判斷是否有字段

數組排序

[self.HelpManager.PublishScopeList sortedArrayUsingComparator:^NSComparisonResult(PublishScopeListModel* obj1, PublishScopeListModel* obj2) {

        NSComparisonResult result = [obj1.num compare:obj2.num];
        return result == NSOrderedAscending; // 降序:NSOrderedAscending====升序:NSOrderedDescending
    }];

為UICollectionView添加頭視圖的兩種方式

• 給UICollectionView添加：UICollectionElementKindSectionHeader
• 設置UICollectionView的：contentInset

- (UICollectionReusableView*)collectionView:(UICollectionView*)collectionView viewForSupplementaryElementOfKind:(NSString*)kind atIndexPath:(NSIndexPath*)indexPath
{
    UICollectionReusableView* cell = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"_CollectionReusableViewIndetifier" forIndexPath:indexPath];
    return cell;
}
- (CGSize)collectionView:(UICollectionView*)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section;
{
    return CGSizeMake(ScreenWidth, 44);
}

    CGFloat _adH = 120.0;
    self.collectionView.contentInset = UIEdgeInsetsMake(_adH, 0, 0, 0);
    [self.adImgeView setFrame:CGRectMake(0, CGRectGetMinY(self.collectionView.frame) - _adH, CGRectGetWidth(self.collectionView.frame), _adH)];

TableViewCell創建技巧

#import <UIKit/UIKit.h>
static NSString* SEGPictorialDetailADCellIdentifier = @"SEGPictorialDetailADCellIdentifier";

static NSString* SEGHelpViewCellIdentifier = @"_SEGHelpViewCellIdentifier";  
static NSString* SEGHelpViewCellDetailTopIdentifier = @"_SEGHelpViewCellDetailTopIdentifier";  
static NSString* SEGHelpViewCellDetailDwonIdentifier = @"_SEGHelpViewCellDetailDwonIdentifier";   


@interface SEGPictorialDetailADCell : UITableViewCell
+ (instancetype)cellWithTableView:(UITableView*)tableView;
+ (instancetype)cellWithTableView:(UITableView*)tableView reuseIdentifier:(NSString*)reuseIdentifier;
@end

#import "SEGPictorialDetailADCell.h"

@implementation SEGPictorialDetailADCell

+ (instancetype)cellWithTableView:(UITableView*)tableView
{
    SEGPictorialDetailADCell* cell = [tableView dequeueReusableCellWithIdentifier:SEGPictorialDetailADCellIdentifier];

    if (cell == nil) {

        cell = [[SEGPictorialDetailADCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:SEGPictorialDetailADCellIdentifier];
    }


    return cell;
}

+ (instancetype)cellWithTableView:(UITableView*)tableView reuseIdentifier:(NSString*)reuseIdentifier
{
    SEGHelpViewCell* cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier];

    if (cell == nil) {
        cell = [[SEGHelpViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:reuseIdentifier];
    }

    return cell;
}

- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString*)reuseIdentifier
{
    self.CellIdentifier = reuseIdentifier;//通過記錄不同的ID來布置對應的界面
    if (self == [super initWithStyle:style reuseIdentifier:reuseIdentifier]) {
    }

    return self;
}
@end

TableHeaderView動態改變高度

[self.tableView beginUpdates];
[self.tableView setTableHeaderView:self.webView];
[self.tableView endUpdates];

去掉多余的空白的cell

self.contactsTableView.tableFooterView = [[UIView alloc] initWithFrame:CGRectZero];

切割圖片

UIImage* Image = [UIImage imageNamed:@"RedButton"];
Image = [logBackgroundImage stretchableImageWithLeftCapWidth:logBackgroundImage.size.width * 0.5 topCapHeight:logBackgroundImage.size.height * 0.5];
[self.loginBtn setBackgroundImage:Image forState:UIControlStateNormal];

實現跳轉safari，phone或message

//調用 電話phone
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"tel://10086"]];

//調用自帶 瀏覽器 safari
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"http://www.baidu.com"]];

//調用 自帶mail
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"mailto://sam@icloud.com"]];

//調用 SMS
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"sms://111111"]];

//跳轉到系統設置相關界面
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:@"prefs:root=WIFI"]];

程序中獲取軟件的版本號和app名稱

應用程序的名稱和版本號等信息都保存在mainBundle的infoDictionary字典中，用下面代碼可以取出來。  
NSDictionary* infoDict =[[NSBundle mainBundle] infoDictionary];  
NSString* versionNum =[infoDict objectForKey:@"CFBundleVersion"];//版本名稱  
NSString*appName =[infoDict objectForKey:@"CFBundleDisplayName"];//app名稱 

在有uinavigation,uitoolbar的情況下，如何添加一個全屏的 uiview （作為顯示一個進度框，任何區域無法觸摸而使用）

[[UIApplication sharedApplication].keyWindow addSubview:waitingview]; 

在項目用代碼打開AppStore

NSString *url = [NSString stringWithFormat:@"http://itunes.apple.com/cn/app/huo-xing-she-xin-dian/id549425594?l=en&mt=8"];  
[[UIApplication sharedApplication] openURL:[NSURL URLWithString:url]];

使屏幕一直保持喚醒狀態？（就是不自動黑屏）

[[UIApplication sharedApplication] setIdleTimerDisabled:YES];

隱藏UINavigationBar

- (void)viewWillAppear:(BOOL)animated
{
    [self.navigationControllersetNavigationBarHidden:YESanimated:YES]; //設置隱藏
    [super viewWillAppear:animated];
}
- (void)viewWillDisappear:(BOOL)animated
{
    [self.navigationControllersetNavigationBarHidden:NOanimated:YES];//設置顯示
    [super viewWillDisappear:animated];
}

在navigationviewcontroller中，pop到指定的VC

NSArray *viewControllers=[self.navigationController viewControllers];  
UIViewController *controller=[viewControllers objectAtIndex:1];  //跳轉到第一個VC
[self.navigationController popToViewController:controller animated:YES];  

獲取手機硬件信息

[[UIDevice currentDevice] systemName];[[UIDevice currentDevice] systemVersion];
[[UIDevice currentDevice] uniqueIdentifier];
[[UIDevice currentDevice] model];
[[UIDevice currentDevice] name];

真機上結果：
System Name: iPhone OSSystem 
Version: 4.2.1
Unique ID: 9b5ded78d5fa0ac96250f8b4af0e46f40b96ea6d
Model: iPhone
Name: “wwk”的 iPhone

模擬器上結果：
System Name: iPhone OSSystem 
Version: 4.2
Unique ID: 21FFE0FF-429B-5D0B-96D2-EADCA3203260
Model: iPhone Simulator
Name: iPhone Simulator

URL編碼、解碼

// 1. URL編碼：ios中http請求遇到漢字的時候，需要轉化成UTF-8：
 NSString* urlString = @"http://www.baidu.com!name=小明";
NSString * encodingString = [urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
//結果：http://www.baidu.com!name=%E5%B0%8F%E6%98%8E

// 2.URL解碼：請求后，返回的數據，如何顯示的是這樣的格式：%3A%2F%2F，此時需要我們進行UTF-8解碼，用到的方法是：
NSString *str = [encodingString stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

獲取URL中的細節

NSURL* url = [NSURL URLWithString:@"http://www.baidu.com/s?tn=baiduhome_pg&bs=NSRUL&f=8&rsv_bp=1&rsv_spt=1&wd=NSurl&inputT=2709"];
    NSLog(@"Scheme: %@", [url scheme]);
    NSLog(@"Host: %@", [url host]);
    NSLog(@"Port: %@", [url port]);
    NSLog(@"Path: %@", [url path]);
    NSLog(@"Relative path: %@", [url relativePath]);
    NSLog(@"Path components as array: %@", [url pathComponents]);
    NSLog(@"Parameter string: %@", [url parameterString]);
    NSLog(@"Query: %@", [url query]);
    NSLog(@"Fragment: %@", [url fragment]);
    NSLog(@"User: %@", [url user]);
    NSLog(@"Password: %@", [url password]);

/*
2016-05-27 11:38:23.503 FourNews[2358:116708] Scheme: http
2016-05-27 11:38:23.504 FourNews[2358:116708] Host: www.baidu.com
2016-05-27 11:38:23.504 FourNews[2358:116708] Port: (null)
2016-05-27 11:38:23.504 FourNews[2358:116708] Path: /s
2016-05-27 11:38:23.504 FourNews[2358:116708] Relative path: /s
2016-05-27 11:38:23.504 FourNews[2358:116708] Path components as array: (
    "/",
    s
)
2016-05-27 11:38:23.504 FourNews[2358:116708] Parameter string: (null)
2016-05-27 11:38:23.505 FourNews[2358:116708] Query: tn=baiduhome_pg&bs=NSRUL&f=8&rsv_bp=1&rsv_spt=1&wd=NSurl&inputT=2709
2016-05-27 11:38:23.505 FourNews[2358:116708] Fragment: (null)
2016-05-27 11:38:23.505 FourNews[2358:116708] User: (null)
2016-05-27 11:38:23.505 FourNews[2358:116708] Password: (null)
*/

獲取URL中的參數

- (NSDictionary*)dictionaryFromQuery:(NSString*)query usingEncoding:(NSStringEncoding)encoding
{
    NSCharacterSet* delimiterSet = [NSCharacterSet characterSetWithCharactersInString:@"&;"];
    NSMutableDictionary* pairs = [NSMutableDictionary dictionary];
    NSScanner* scanner = [[NSScanner alloc] initWithString:query];
    while (![scanner isAtEnd]) {
        NSString* pairString = nil;
        [scanner scanUpToCharactersFromSet:delimiterSet intoString:&pairString];
        [scanner scanCharactersFromSet:delimiterSet intoString:NULL];
        NSArray* kvPair = [pairString componentsSeparatedByString:@"="];
        if (kvPair.count == 2) {
            NSString* key = [[kvPair objectAtIndex:0]
                stringByReplacingPercentEscapesUsingEncoding:encoding];
            NSString* value = [[kvPair objectAtIndex:1]
                stringByReplacingPercentEscapesUsingEncoding:encoding];
            [pairs setObject:value forKey:key];
        }
    }

    return [NSDictionary dictionaryWithDictionary:pairs];
}

[**ViewController respondsToSelector:]: message sent to deallocated instance崩潰問題解決方法

這是因為這個UIViewController釋放后，又再次向這個VC調用了某些請求導致的，一般出現這種報錯是UIViewController里面有設置xxx.delegate=self，這些代理有延時方法，例如等待網絡返回等
當導航欄直接返回時，UIViewController已經被銷毀，延時方法再調用此野指針VC，便會導致崩潰
解決方法：
1 在dealloc中設置xx.delegate = nil ，這個是程序沒有使用ARC才可以
2 在viewWillDisappear方法中把所有xxx.delegate=self的具有延時方法的delegate置nil，我的做法是不過有沒有延時方法，

UIView有關的雜技

//設置View的圓角：
[view.layer setCornerRadius:15.0];