iOS開發基礎知識--片段46

標籤：

1:帶中文的URL處理

// http://static.tripbe.com/videofiles/視頻/我的自拍視頻.mp4NSString *path  = (__bridge_transfer NSString *)CFURLCreateStringByReplacingPercentEscapesUsingEncoding(NULL,(__bridge CFStringRef)model.mp4_url, CFSTR(""),CFStringConvertNSStringEncodingToEncoding(NSUTF8StringEncoding));

2:取WebView高度

- (void)webViewDidFinishLoad:(UIWebView *)webView  {      CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];      CGRect frame = webView.frame;      webView.frame = CGRectMake(frame.origin.x, frame.origin.y, frame.size.width, height);  }  

另外一種方式利用KVO執行個體：-(void)viewDidLoad{    // KVO,作為一個觀察者,只要屬性"contentSize"發生變化,回調方法裡面就會通知    [_webView.scrollView addObserver:self forKeyPath:@"contentSize" options:NSKeyValueObservingOptionNew context:NULL];}//  回調方法- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{    if(object == _webView.scrollView && [keyPath isEqualToString:@"contentSize"])    {        //  得到最大的Y座標        CGSize size = _webView.scrollView.contentSize;              if (size.height > 568.0) {                        // 遮擋廣告            _hideBottomImage = [[UIImageView alloc] initWithFrame:CGRectMake(0, size.height-67, ScreenWidth, 67)];            _hideBottomImage.image = [UIImage imageNamed:@"banner"];            [_webView.scrollView addSubview:_hideBottomImage];        }    }    else    {        //  調用父類的方法        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];    }}- (void)dealloc{//---->在ARC環境下也能調用dealloc方法,只是不需要寫[super dealloc]    // 移除KVO,否則會引起資源流失     [_webView.scrollView removeObserver:self forKeyPath:@"contentSize"];}

 

3:UIView的部分圓角問題

UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(120, 10, 80, 80)];view2.backgroundColor = [UIColor redColor];[self.view addSubview:view2]; UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:view2.bounds byRoundingCorners:UIRectCornerBottomLeft | UIRectCornerBottomRight cornerRadii:CGSizeMake(10, 10)];CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];maskLayer.frame = view2.bounds;maskLayer.path = maskPath.CGPath;view2.layer.mask = maskLayer;//其中，byRoundingCorners:UIRectCornerBottomLeft |UIRectCornerBottomRight//指定了需要成為圓角的角。該參數是UIRectCorner類型的，可選的值有：* UIRectCornerTopLeft* UIRectCornerTopRight* UIRectCornerBottomLeft* UIRectCornerBottomRight* UIRectCornerAllCorners

4：強制App直接退出

- (void)exitApplication {    AppDelegate *app = [UIApplication sharedApplication].delegate;    UIWindow *window = app.window;    [UIView animateWithDuration:1.0f animations:^{        window.alpha = 0;    } completion:^(BOOL finished) {        exit(0);    }];}

5：修改預留位置顏色和大小

textField.placeholder = @"請輸入使用者名稱";  [textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];  [textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

6：取消系統的返回手勢

self.navigationController.interactivePopGestureRecognizer.enabled = NO;

7：改WebView字型/顏色

UIWebView設定字型大小，顏色，字型： UIWebView無法通過自身的屬性設定字型的一些屬性，只能通過html代碼進行設定 在webView載入完畢後：

- (void)webViewDidFinishLoad:(UIWebView *)webView {      NSString *str = @"document.getElementsByTagName(‘body‘)[0].style.webkitTextSizeAdjust= ‘60%‘";      [webView stringByEvaluatingJavaScriptFromString:str]; }或者加入以下代碼NSString *jsString = [[NSString alloc] initWithFormat:@"document.body.style.fontSize=%f;document.body.style.color=%@",fontSize,fontColor];   [webView stringByEvaluatingJavaScriptFromString:jsString];

8：WebView圖片自適應螢幕

- (void)webViewDidFinishLoad:(UIWebView *)webView {  NSString *js = @"function imgAutoFit() {      var imgs = document.getElementsByTagName(‘img‘);      for (var i = 0; i < imgs.length; ++i) {        var img = imgs[i];           img.style.maxWidth = %f;        }   }";  js = [NSString stringWithFormat:js, [UIScreen mainScreen].bounds.size.width - 20];   [webView stringByEvaluatingJavaScriptFromString:js];  [webView stringByEvaluatingJavaScriptFromString:@"imgAutoFit()"];}

9：BOOL / bool / Boolean / NSCFBoolean的區別

10：nil / Nil / NULL / NSNull區別

a、nil：一般賦值給Null 物件；

b、NULL：一般賦值給nil之外的其他空值。如SEL等；

　　舉個栗子（好重啊~）：

　　　　[NSApp beginSheet:sheet
             　　 modalForWindow:mainWindow

              　　modalDelegate:nil //pointing to an object

              　　didEndSelector:NULL //pointing to a non object/class

              　　contextInfo:NULL]; //pointing to a non object/class

c、NSNULL：NSNull只有一個方法：+ (NSNull *) null;

　　[NSNull null]用來在NSArray和NSDictionary中加入非nil（表示列表結束）的空值.

NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionary];mutableDictionary[@"someKey"] = [NSNull null]; // Sets value of NSNull singleton for `someKey`NSLog(@"Keys: %@", [mutableDictionary allKeys]); // @[@"someKey"]

d、當向nil發送訊息時，返回NO，不會有異常，程式將繼續執行下去；

　　而向NSNull的對象發送訊息時會收到異常。

 

11:子類中實現 -isEqual: 和 hash

@interface Person@property NSString *name;@property NSDate *birthday;- (BOOL)isEqualToPerson:(Person *)person;@end@implementation Person- (BOOL)isEqualToPerson:(Person *)person {  if (!person) {    return NO;  }  BOOL haveEqualNames = (!self.name && !person.name) || [self.name isEqualToString:person.name];  BOOL haveEqualBirthdays = (!self.birthday && !person.birthday) || [self.birthday isEqualToDate:person.birthday];  return haveEqualNames && haveEqualBirthdays;}#pragma mark - NSObject- (BOOL)isEqual:(id)object {  if (self == object) {    return YES;  }  if (![object isKindOfClass:[Person class]]) {    return NO;  }  return [self isEqualToPerson:(Person *)object];}- (NSUInteger)hash {  return [self.name hash] ^ [self.birthday hash];}

iOS開發基礎知識--片段46