iOS之常用的方法和技巧

判断字符串是不是以中文开头

- (BOOL)isChineseFirst:(NSString *)firstString { //是否以中文开头(unicode中文编码范围是0x4e00~0x9fa5) int utfCode = 0; void *buffer = &utfCode; NSRange range = NSMakeRange(0, 1); //判断是不是中文开头的,buffer->获取字符的字节数据 maxLength->buffer的最大长度 usedLength->实际写入的长度，不需要的话可以传递NULL encoding->字符编码常数，不同编码方式转换后的字节长是不一样的，这里我用了UTF16 Little-Endian，maxLength为2字节，如果使用Unicode，则需要4字节 options->编码转换的选项，有两个值，分别是NSStringEncodingConversionAllowLossy和NSStringEncodingConversionExternalRepresentation range->获取的字符串中的字符范围,这里设置的第一个字符 remainingRange->建议获取的范围，可以传递NULL BOOL isChinese = [firstString getBytes:buffer maxLength:2 usedLength:NULL encoding:NSUTF16LittleEndianStringEncoding options:NSStringEncodingConversionExternalRepresentation range:range remainingRange:NULL]; if (isChinese && (utfCode >= 0x4e00 && utfCode <= 0x9fa5)) return YES; else return NO; }

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键盘回收

- (void)setUpForDismissKeyboard { UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapAnywhereToDismissKeyboard:)]; NSOperationQueue *operation = [NSOperationQueue mainQueue]; [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillShowNotification object:nil queue:operation usingBlock:^(NSNotification * _Nonnull note) { [self.view addGestureRecognizer:tapGesture]; }]; [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillHideNotification object:nil queue:operation usingBlock:^(NSNotification * _Nonnull note) { [self.view removeGestureRecognizer:tapGesture]; }]; }

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禁止侧滑返回上一个界面

if ([self.navigationController respondsToSelector:@selector(interactivePopGestureRecognizer)]) { self.navigationController.interactivePopGestureRecognizer.enabled = NO; }

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隐藏导航栏最下面的黑线

- (void)hiddenNavLine { if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)]){ NSArray *list=self.navigationController.navigationBar.subviews; for (id obj in list) { if ([UIDevice currentDevice].systemVersion.floatValue >= 10.0) { UIView *view = (UIView*)obj; for (id obj2 in view.subviews) { if ([obj2 isKindOfClass:[UIImageView class]]) { UIImageView *image = (UIImageView*)obj2; image.hidden = YES; } } } } } }

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去除自带的searchBar的背景View

- (void)removeSearchBarBackGroundView { for(int i = 0 ;i < _searchBar.subviews.count;i++){ UIView * backView = _searchBar.subviews[i]; if ([backView isKindOfClass:NSClassFromString(@"UISearchBarBackground")] == YES) { [backView removeFromSuperview]; [_searchBar setBackgroundColor:[UIColor clearColor]]; break; } else { NSArray * arr = _searchBar.subviews[i].subviews; for(int j = 0;j < arr.count; j++){ UIView * barView = arr[i]; if ([barView isKindOfClass:NSClassFromString(@"UISearchBarBackground")] == YES) { [barView removeFromSuperview]; [_searchBar setBackgroundColor:[UIColor clearColor]]; break; } } } } }

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标签栏的背景图显示错乱问题解决办法：

//将图片如下设置 [[UIImage imageNamed:@"me@2x.png"] imageWithRenderingMode:UIImageRenderingModeAlwaysOriginal]

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网络请求设置超时请求（基于AFNetworking3.0封装的GET，POST请求用方法）

AFHTTPSessionManager *manager = [AFHTTPSessionManager manager]; [manager.requestSerializer willChangeValueForKey:@"timeoutInterval"]; manager.requestSerializer.timeoutInterval = 15.f; [manager.requestSerializer didChangeValueForKey:@"timeoutInterval"];

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实用的获取图片的方法，防止内存溢出：

// 建议使用该方法： NSString *imagePath = [[NSBundle mainBundle] pathForResource:@"图片" ofType:@"png"]; UIImage *image = [[UIImage alloc] initWithContentsOfFile:imagePath]; // 不建议使用该方法： UIImage *image = [UIImage imageNamed:@"图片.png"];

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iOS

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