nslog to file

- (void)redirectLogToDocuments {
    NSArray *allPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [allPaths objectAtIndex:0];
    NSString *pathForLog = [documentsDirectory stringByAppendingPathComponent:@"logFile.txt"];
  
    if ([[NSFileManager defaultManager] fileExistsAtPath:pathForLog]) {
        NSError *error;
        [[NSFileManager defaultManager] removeItemAtPath:pathForLog error:&error];
        if (error!=nil) {
            NSLog(@"%@", error.localizedDescription);
        }
    }
    freopen([pathForLog cStringUsingEncoding:NSASCIIStringEncoding],"a+",stderr);
}

讓圖示在AttributedText上下置中

https://stackoverflow.com/questions/26105803/center-nstextattachment-image-next-to-single-line-uilabel

let iconImage = UIImage(named: "icon.png")!
var icon = NSTextAttachment()
icon.bounds = CGRect(x: 0, y: (titleFont.capHeight - iconImage.size.height).rounded() / 2, width: iconImage.size.width, height: iconImage.size.height)
icon.image = iconImage
let iconString = NSAttributedString(attachment: icon)
titleText.append(iconString)

rate the app

- (IBAction)rateButtonTapped:(UIButton *)sender {
    if (@available(iOS 10.3, *)) {
        [SKStoreReviewController requestReview];
    } else {
        NSURL *url = [NSURL URLWithString:@"itms-apps://itunes.apple.com/tw/app/swipedon-visitor-management/id986185962?l=en&mt=8"];
        [[UIApplication sharedApplication] openURL:url];
    }
}

用CoreData存圖片

不要用core data存圖
是可以轉存NSData去存，但只要你的ManagedObjectContext沒有釋放，那麼那張圖就不會被釋放，如果圖片大一點，一下就爆了

用core data存imageName，把圖片存到文件資料夾裡，用imageName去對應，
並且監聽imageName的setter，在改名之前先刪去原來的圖。

block中的self

Medium上有一篇文章說用_variable取代self.variable 就不會循環引用
實驗之後發現：
_variable也會
還是宣告成weak最好

既使weakSelf去呼叫一個方法，方法裡面有不是weak的self，那還是不會循環引用的。

用變數型態直接宣告在.h或.m，就算加了__weak還是一樣會循環引用，得要改成property的型態並宣告成weak才能避免

如果你在block中使用一些singleton例如[UIApplication sharedApplication]，只要不要用變數去接它，就可以安全下莊

WKWebView

// Inject新的attribute給你的wkwebview
- (void)setupWebView {
    NSString *jScript = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('initial-scale', '1'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
  
    WKUserScript *userScript = [[WKUserScript alloc] initWithSource:jScript injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
    WKUserContentController *userContentController = [[WKUserContentController alloc] init];
    [userContentController addUserScript:userScript];
  
    WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
    wkWebConfig.userContentController = userContentController;
  
// 因為pdf的高度用webview的寬度去調整，所以要先設定好。
    CGRect initialWebViewFrame = self.view.frame;
    if ([[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortrait ||
         [[UIApplication sharedApplication] statusBarOrientation] == UIInterfaceOrientationPortraitUpsideDown) {
        CGFloat height = initialWebViewFrame.size.height;
        CGFloat width = initialWebViewFrame.size.width;
        if (height > width) {
            initialWebViewFrame.size = CGSizeMake(width, 0);
        } else {
            initialWebViewFrame.size = CGSizeMake(height, 0);
        }
    }
    _webView = [[WKWebView alloc] initWithFrame:initialWebViewFrame configuration:wkWebConfig];
    _webView.scrollView.contentSize = initialWebViewFrame.size;
    [_webViewContainer addSubview:_webView];
    _webView.navigationDelegate = self;
    [_webViewContainer addConstraint:[NSLayoutConstraint constraintWithItem:_webView attribute:NSLayoutAttributeTop relatedBy:NSLayoutRelationEqual toItem:_webViewContainer attribute:NSLayoutAttributeTop multiplier:1.0 constant:0]];
    [_webViewContainer addConstraint:[NSLayoutConstraint constraintWithItem:_webView attribute:NSLayoutAttributeHeight relatedBy:NSLayoutRelationEqual toItem:_webViewContainer attribute:NSLayoutAttributeHeight multiplier:1.0 constant:0]];
    [_webViewContainer addConstraint:[NSLayoutConstraint constraintWithItem:_webView attribute:NSLayoutAttributeLeading relatedBy:NSLayoutRelationEqual toItem:_webViewContainer attribute:NSLayoutAttributeLeading multiplier:1.0 constant:0]];
    [_webViewContainer addConstraint:[NSLayoutConstraint constraintWithItem:_webView attribute:NSLayoutAttributeTrailing relatedBy:NSLayoutRelationEqual toItem:_webViewContainer attribute:NSLayoutAttributeTrailing multiplier:1.0 constant:0]];
  
    _webView.scrollView.scrollEnabled = NO;
    [_webView.scrollView setBackgroundColor:[UIColor clearColor]];
    [_webView setBackgroundColor:[UIColor clearColor]];
    [_webView setOpaque:NO];
}

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation {
    if ([[SettingsManager sharedManager].agreement[@"agreement_type"] isEqualToString:@"pdf"]) {

    } else {
        if (shouldReloadFlag) {
            shouldReloadFlag = NO;
            [self loadWebView];
        }
    }
    [self resizeScrollView];
}

- (void)resizeScrollView {
    if ([[SettingsManager sharedManager].agreement[@"agreement_type"] isEqualToString:@"pdf"]) {
        if (_webView.isLoading == false) {
            for (UIView *subview in self.webView.scrollView.subviews) {
                subview.backgroundColor = [UIColor clearColor];

// 取得pdf的高
                if ([[[subview class] description] isEqualToString:@"WKPDFView"]) {
                    NSLog(@"pdfview.size: %@ webviewContainer.size:%@", NSStringFromCGSize(subview.frame.size), NSStringFromCGSize(_webViewContainer.frame.size));
                    [self resizeScrollViewByWebViewContentHeight:subview.frame.size.height / subview.frame.size.width * _webViewContainer.frame.size.width];
                    break;
                }
            }
        }
    } else {
        if (_webView.isLoading == false) {
            __weak typeof(self) weakSelf = self;
            [_webView evaluateJavaScript:@"document.body.offsetHeight" completionHandler:^(id result, NSError * _Nullable error) {
                CGFloat height = [result floatValue] + 30.0;
                [weakSelf resizeScrollViewByWebViewContentHeight:height];
            }];
        }
    }
}

keyboard disappaer when tableView scrolling

筆記一下這個坑：
在前人的code裡一直找不到endEditing or resignFirstResponder 寫在那裡，但每次一動tableview小鍵盤就消失，最後才找到是在storyboard裡面被設定了


如果要手動設定的話，是下面這個property

self.tableView.keyboardDismissMode = UIScrollViewKeyboardDismissModeInteractive;