1.字符串處理: 截取字符串

• -(NSString *)substringToIndex:(NSUInteger)to;
• 不包括index處字符
• 判斷字符串長(zhǎng)度,否則可能崩潰

2.在導(dǎo)航欄添加UIBarButtonItem時(shí),在iOS7后會(huì)進(jìn)行自動(dòng)渲染

img = [img imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal];

3.遍歷數(shù)組刪除某個(gè)元素(不要forin正序遍歷時(shí)刪除,會(huì)崩潰)

• 逆序遍歷,然后查找刪除

NSEnumerator *enumerator = [array reverseObjectEnumerator];  
//forin遍歷  
for (AddressPerson *groupName in enumerator) {  
    if ([[groupName group] isEqualToString:@"Zhangsan"]) {  
        [array removeObject:groupName];  
    }  
} 

• 定義一個(gè)副本,遍歷副本找到想要?jiǎng)h除的元素index,然后在原數(shù)組中刪除對(duì)應(yīng)的元素

4. 數(shù)組元素去重

• 利用NSSet的allObjects方法

  NSSet *set = [NSSet setWithArray:dataArray];  
   NSLog(@"%@",[set allObjects]); 

• 利用數(shù)組的containsObject來去除

    NSMutableArray *listAry = [[NSMutableArray alloc]init];  
    for (NSString *str in dataArray) {  
        if (![listAry containsObject:str]) {  
            [listAry addObject:str];  
        }  
    }  
    NSLog(@"%@",listAry);  

• 利用NSDictionary的AllKeys（AllValues）方法

NSArray *dataArray = @[@"2014-04-01",@"2014-04-02",@"2014-04-03",
                           @"2014-04-01",@"2014-04-02",@"2014-04-03",
                           @"2014-04-01",@"2014-04-03",@"2014-04-03",
                           @"2014-04-01",@"2014-04-02",@"2014-04-03",
                           @"2014-04-01",@"2014-04-02",@"2014-04-03",
                           @"2014-04-01",@"2014-04-02",@"2014-04-03",
                           @"2014-04-04",@"2014-04-06",@"2014-04-08",
                           @"2014-04-05",@"2014-04-07",@"2014-04-09",];
    NSMutableDictionary *dic = [[NSMutableDictionary alloc]initWithCapacity:0];
    for(NSString *str in dataArray)
    {
        [dic setValue:str forKey:str];
    }
    NSLog(@"%@",[dic allKeys]);

5. 如果設(shè)置了啟動(dòng)圖片而沒有生效,需要將原來的程序卸載在運(yùn)行即可.

6.添加4s模擬器

• /Applications(應(yīng)用程序)/Xcode.app(顯示包內(nèi)容)/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/Library/CoreSimulator/Profiles/Runtimes 后面兩級(jí)目錄需要自己創(chuàng)建

• Xcode 顯示包內(nèi)容 Contents-->Developer-->Platforms-->iPhoneOS.platform-->DeviceSupport
  /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/DeviceSupport

7.通過狀態(tài)欄判斷當(dāng)前的網(wǎng)絡(luò)連接狀態(tài)

 /*
 * 0 = No wifi or cellular
 * 1 = 2G and earlier? (not confirmed)
 * 2 = 3G? (not yet confirmed)
 * 3 = 4G
 * 4 = LTE
 * 5 = Wifi
 */

- (int)dataNetworkTypeFromStatusBar
{
    UIApplication *app = [UIApplication sharedApplication];
    
    NSArray *subviews = [[[app valueForKey:@"statusBar"] valueForKey:@"foregroundView"] subviews];
    NSNumber *dataNetworkItemView = nil;
    
    for (id subview in subviews) {
        if([subview isKindOfClass:[NSClassFromString(@"UIStatusBarDataNetworkItemView") class]]) {
            dataNetworkItemView = subview;
            break;
        }
    }
    
    int netType = 0;
    NSNumber * num = [dataNetworkItemView valueForKey:@"dataNetworkType"];
    if (num == nil) {
        netType = 0;
    }else{
        int n = [num intValue];
        if (n == 0) {
            netType = 0;
        }else if (n == 1){
            netType = 1;
        }else if (n == 2){
            netType = 2;
        }else{
            netType = 3;
        }
    }
    return netType;
}


 # import <CoreTelephony/CTTelephonyNetworkInfo.h>  
 # import <CoreTelephony/CTCarrier.h>

**獲取運(yùn)營(yíng)商信息**  
-(void)getcarrierName{  
    CTTelephonyNetworkInfo *telephonyInfo = [[CTTelephonyNetworkInfo alloc] init];  
    CTCarrier *carrier = [telephonyInfo subscriberCellularProvider];  
    NSString *currentCountry=[carrier carrierName];  
    NSLog(@"[carrier isoCountryCode]==%@,[carrier allowsVOIP]=%d,[carrier mobileCountryCode=%@,[carrier mobileCountryCode]=%@",[carrier isoCountryCode],[carrier allowsVOIP],[carrier mobileCountryCode],[carrier mobileNetworkCode]);  
    serverLabel.text=currentCountry;  
}  

8.搜索框添加 “廣告”標(biāo)簽

- (void)addADFlagOnSearchBar {
    NSString *key = [self.requestDict objectForKey:@"key"];
    if (key && key.length > 0) {
        self.searchBar.showsSearchResultsButton = NO;
    } else {
        self.searchBar.showsSearchResultsButton = YES;
        NSString *imageName = (iPhone6Plus? @"xfList_AD_iPhone6plus_icon.png": @"xfList_AD_iPhone5_icon.png");
        [self.searchBar setImage:[UIImage imageNamed:imageName] forSearchBarIcon:UISearchBarIconResultsList state:UIControlStateNormal];
        UITextField *searchField = [self.searchBar valueForKey:@"_searchField"];
        if (searchField) {
            searchField.rightView.bounds = CGRectMake(0, 0, 27, 14);
            searchField.rightViewMode    = UITextFieldViewModeUnlessEditing;
        }
        [self.searchBar setPositionAdjustment:UIOffsetMake(5, 0) forSearchBarIcon:UISearchBarIconResultsList];
    }
}

9.禁止手機(jī)睡眠 參考鏈接

UIApplication.shared.isIdleTimerDisabled = true

iOS8系統(tǒng)中丸相，tableView最好實(shí)現(xiàn)下-tableView: heightForRowAtIndexPath:這個(gè)代理方法，要不然在iOS8中可能就會(huì)出現(xiàn)顯示不全或者無法響應(yīng)事件的問題

// 必須寫的方法般眉，和editActionsForRowAtIndexPath配對(duì)使用凳鬓，里面什么不寫也行
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

}

10.collectionView的內(nèi)容小于其寬高的時(shí)候是不能滾動(dòng)的罐监，設(shè)置可以滾動(dòng)：

collectionView.alwaysBounceHorizontal = YES;
collectionView.alwaysBounceVertical = YES;

11.強(qiáng)引用 / 弱引用????

#define WeakSelf(type)  __weak typeof(type) weak##type = type; // weak
#define StrongSelf(type)  __strong typeof(type) type = weak##type; // strong

[textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
[textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

12.image圓角

- (UIImage *)circleImage
{
    // NO代表透明
    UIGraphicsBeginImageContextWithOptions(self.size, NO, 1);
    // 獲得上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    // 添加一個(gè)圓
    CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
    // 方形變圓形
    CGContextAddEllipseInRect(ctx, rect);
    // 裁剪
    CGContextClip(ctx);
    // 將圖片畫上去
    [self drawInRect:rect];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

+ (UIImage *)resizableImage:(NSString *)imageName
{
    UIImage *image = [UIImage imageNamed:imageName];
    CGFloat imageW = image.size.width;
    CGFloat imageH = image.size.height;
    return [image resizableImageWithCapInsets:UIEdgeInsetsMake(imageH * 0.5, imageW * 0.5, imageH * 0.5, imageW * 0.5) resizingMode:UIImageResizingModeStretch];
}

13.身份證號(hào)驗(yàn)證

- (BOOL)validateIdentityCard {
    BOOL flag;
    if (self.length <= 0) {
        flag = NO;
        return flag;
    }
    NSString *regex2 = @"^(\\d{14}|\\d{17})(\\d|[xX])$";
    NSPredicate *identityCardPredicate = [NSPredicate predicateWithFormat:@"SELF MATCHES %@",regex2];
    return [identityCardPredicate evaluateWithObject:self];
}

14.拿到當(dāng)前正在顯示的控制器裂问，不管是push進(jìn)去的豫缨，還是present進(jìn)去的都能拿到

- (UIViewController *)getVisibleViewControllerFrom:(UIViewController*)vc {
    if ([vc isKindOfClass:[UINavigationController class]]) {
        return [self getVisibleViewControllerFrom:[((UINavigationController*) vc) visibleViewController]];
    }else if ([vc isKindOfClass:[UITabBarController class]]){
        return [self getVisibleViewControllerFrom:[((UITabBarController*) vc) selectedViewController]];
    } else {
        if (vc.presentedViewController) {
            return [self getVisibleViewControllerFrom:vc.presentedViewController];
        } else {
            return vc;
        }
    }
}

15.真機(jī)測(cè)試的時(shí)候報(bào)錯(cuò)：Could not launch "你的 App"谒兄，process launch failed: Security

• 因?yàn)槟愕腶pp沒有上線摔桦，iOS9開始社付，需要手動(dòng)信任Xcode生成的描述文件承疲，打開手機(jī)設(shè)置->通用->描述文件->點(diǎn)擊你的app的描述文件->點(diǎn)擊信任

真機(jī)測(cè)試的時(shí)候報(bào)錯(cuò)：Could not find Developer Disk Image

• 這是因?yàn)槟愕脑O(shè)備系統(tǒng)版本大于Xcode能兼容的系統(tǒng)版本邻耕，比如你的設(shè)備是iOS10.3，而Xcode版本是8.2（Xcode8.2最大兼容iOS10.2）燕鸽，就會(huì)報(bào)這個(gè)錯(cuò)誤兄世。解決辦法就是升級(jí)Xcode！

16.移除字符串中的空格和換行

+ (NSString *)removeSpaceAndNewline:(NSString *)str {
    NSString *temp = [str stringByReplacingOccurrencesOfString:@" " withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\r" withString:@""];
    temp = [temp stringByReplacingOccurrencesOfString:@"\n" withString:@""];
    return temp;
}

17.字符串是否為空

+ (BOOL)isEqualToNil:(NSString *)str {
    return str.length <= 0 || [str isEqualToString:@""] || !str;
}

18.判斷字符串中是否有空格

+ (BOOL)isBlank:(NSString *)str {
    NSRange _range = [str rangeOfString:@" "];
    if (_range.location != NSNotFound) {
        //有空格
        return YES;
    } else {
        //沒有空格
        return NO;
    }
}

19.從NSURL中拿到鏈接字符串

NSString *urlString = myURL.absoluteString;

20.如果用addTarget:action:forControlEvents:方法為一個(gè)button添加了很多點(diǎn)擊事件啊研，在某個(gè)時(shí)刻想一次刪除怎么辦御滩？只需要調(diào)用下邊這句代碼

[youButton removeTarget:nil action:nil forControlEvents:UIControlEventAllEvents];

21.tableViewCell分割線頂?shù)筋^

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    [cell setSeparatorInset:UIEdgeInsetsZero];
    [cell setLayoutMargins:UIEdgeInsetsZero];
    cell.preservesSuperviewLayoutMargins = NO;
}

- (void)viewDidLayoutSubviews {
    [self.tableView setSeparatorInset:UIEdgeInsetsZero];
    [self.tableView setLayoutMargins:UIEdgeInsetsZero];
}

防止離屏渲染為image添加圓角

// image分類
- (UIImage *)circleImage
{
// NO代表透明
UIGraphicsBeginImageContextWithOptions(self.size, NO, 1);
// 獲得上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();
// 添加一個(gè)圓
CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height);
// 方形變圓形
CGContextAddEllipseInRect(ctx, rect);
// 裁剪
CGContextClip(ctx);
// 將圖片畫上去
[self drawInRect:rect];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;
}

22.判斷rect是否相等交叉

// 是否相交
 if (CGRectIntersectsRect(rect1, rect2)) {
}
if (CGRectEqualToRect(rect1, rect2)) { // 兩個(gè)區(qū)域相等
        // do some
    }
    if (CGPointEqualToPoint(point1, point2)) { // 兩個(gè)點(diǎn)相等
        // do some
    }
    if (CGSizeEqualToSize(size1, size2)) { // 兩個(gè)size相等
        // do some
    }

23.判斷字符串是否為數(shù)字

NSCharacterSet *notDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    if ([str rangeOfCharacterFromSet:notDigits].location == NSNotFound)
    {
      // 是數(shù)字
    } else
    {
      // 不是數(shù)字
    }

23、判斷一個(gè)view是否為另一個(gè)view的子視圖

// 如果myView是self.view本身党远，也會(huì)返回yes
BOOL isSubView = [myView isDescendantOfView:self.view];

24.UIWebView添加單擊手勢(shì)不響應(yīng)

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(webViewClick)];
        tap.delegate = self;
        [_webView addGestureRecognizer:tap];

// 因?yàn)閣ebView本身有一個(gè)單擊手勢(shì)削解，所以再添加會(huì)造成手勢(shì)沖突，從而不響應(yīng)沟娱。需要綁定手勢(shì)代理氛驮，并實(shí)現(xiàn)下邊的代理方法
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{
    return YES;
}

25 字符串轉(zhuǎn)數(shù)值問題

• 非純數(shù)字的字符串轉(zhuǎn)doublevalue floatvalue 都是 0
• 如和判斷一個(gè)字符串是否為數(shù)字和小數(shù)點(diǎn)

- (BOOL)isPureNumandCharacters:(NSString *)string
{
    NSCharacterSet *numberSet = [NSCharacterSet characterSetWithCharactersInString:@"0123456789."];
    string = [string stringByTrimmingCharactersInSet:numberSet];
    if(string.length > 0)
    {
        return NO;
    }
    return YES;
}

26 字符串包含

- (BOOL)containsString:(NSString *)str

• str不能為nil,否則會(huì)崩潰
• API_AVAILABLE ios(8.0)