iOS小点整理

1、设置navigationBar title的颜色

UIColor *whiteColor = [UIColor whiteColor];
NSDictionary *dic = [NSDictionary dictionaryWithObject:whiteColor forKey:NSForegroundColorAttributeName];
[self.navigationController.navigationBar setTitleTextAttributes:dic];

2、修改textField的placeholder的字体颜色、大小

a.通过kvo设置
self.textField.placeholder = @"请输入商品名称";
[self.textField setValue:[UIColor redColor] forKeyPath:@"_placeholderLabel.textColor"];
[self.textField setValue:[UIFont boldSystemFontOfSize:16] forKeyPath:@"_placeholderLabel.font"];

b.通过富文本设置
NSString *string = @"请输入商品名称";
NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:string];

[attributedString addAttribute:NSForegroundColorAttributeName
                             value:[UIColor redColor]
                             range:NSMakeRange(0, [string length])];
 
[attributedString addAttribute:NSFontAttributeName
                             value:[UIFont systemFontOfSize:16]
                             range:NSMakeRange(0, [string length])];
 
self.textField.attributedPlaceholder = attributedString;

3、关闭/收起键盘方法

a.点击Return按扭时收起键盘
-(BOOL)textFieldShouldReturn:(UITextField*)textField{
    return [textField resignFirstResponder]; 
}

b.点击背景View收起键盘
[self.view endEditing:YES];

c.在任何地方统一收起键盘
[[[UIApplication sharedApplication] keyWindow] endEditing:YES];

4、将color转为UIImage

-(UIImage*)createImageWithColor:(UIColor*)color{
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return theImage;
}

5、NSString进行URL编码转换

urlStr = [urlStr stringByAddingPercentEscapesUsingEncoding: NSUTF8StringEncoding];

6、清理内存

// 清理内存
[[SDImageCache sharedImageCache] clearMemory];
 
// 清理webview 缓存
NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage];
for (NSHTTPCookie *cookie in [storage cookies]) {
    [storage deleteCookie:cookie];
}
 
NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
[config.URLCache removeAllCachedResponses];
[[NSURLCache sharedURLCache] removeAllCachedResponses];
 
// 清理硬盘
[[SDImageCache sharedImageCache] clearDiskOnCompletion:^{
    [MBProgressHUD hideAllHUDsForView:self.view animated:YES];
 
    [self.tableView reloadData];
}];

7、返回一个没有重复元素的数组

-(NSArray *)arrayWithMemberIsOnly:(NSArray *)array{
    NSMutableArray *categoryArray = [[NSMutableArray alloc] init];
    for (unsigned i = 0; i < [array count]; i++) {
       if ([categoryArray containsObject:[array objectAtIndex: i]] == NO) {
           [categoryArray addObject:[array objectAtIndex: i]];
       }
    }
   return categoryArray;
}

8、限制UITextField字数

-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
    if (textField.text.length + string.length > 18) {
        return NO;
    }
    if (textField.text.length < range.location + range.length) {
        return NO;
    }
    return YES;
}

9、隐私数据访问问题
项目中访问了隐私数据,比如:相机,相册,联系人等,在Xcode8中打开编译的话,统统会crash.提交App Store会被拒绝，可以才info.plist中添加如下设置：

<!-- 相册 --> 
<key>NSPhotoLibraryUsageDescription</key> 
<string>App需要您的同意,才能访问相册</string> 
<!-- 相机 --> 
<key>NSCameraUsageDescription</key> 
<string>App需要您的同意,才能访问相机</string> 
<!-- 麦克风 --> 
<key>NSMicrophoneUsageDescription</key> 
<string>App需要您的同意,才能访问麦克风</string> 
<!-- 位置 --> 
<key>NSLocationUsageDescription</key> 
<string>App需要您的同意,才能访问位置</string> 
<!-- 在使用期间访问位置 --> 
<key>NSLocationWhenInUseUsageDescription</key> 
<string>App需要您的同意,才能在使用期间访问位置</string> 
<!-- 始终访问位置 --> 
<key>NSLocationAlwaysUsageDescription</key> 
<string>App需要您的同意,才能始终访问位置</string> 
<!-- 日历 --> 
<key>NSCalendarsUsageDescription</key> 
<string>App需要您的同意,才能访问日历</string> 
<!-- 提醒事项 --> 
<key>NSRemindersUsageDescription</key> 
<string>App需要您的同意,才能访问提醒事项</string> 
<!-- 运动与健身 --> 
<key>NSMotionUsageDescription</key> <string>App需要您的同意,才能访问运动与健身</string> 
<!-- 健康更新 --> 
<key>NSHealthUpdateUsageDescription</key> 
<string>App需要您的同意,才能访问健康更新 </string> 
<!-- 健康分享 --> 
<key>NSHealthShareUsageDescription</key> 
<string>App需要您的同意,才能访问健康分享</string> 
<!-- 蓝牙 --> 
<key>NSBluetoothPeripheralUsageDescription</key> 
<string>App需要您的同意,才能访问蓝牙</string> 
<!-- 媒体资料库 --> 
<key>NSAppleMusicUsageDescription</key> 
<string>App需要您的同意,才能访问媒体资料库</string>

10、银行卡校验码算法

-(void)getBankCardCheckCode{

    NSString *cardNumber = @"625965087177209";
    NSMutableString *checkCode = [NSMutableString string];
    //校验码为银行卡号最后一位，采用LUHN算法，亦称模10算法。计算方法如下：
   
    for (NSInteger i = 0; i < cardNumber.length; i+=2) {
        //第一步：从右边第1个数字开始每隔一位乘以2；
        NSString *str = [cardNumber substringWithRange:NSMakeRange(i, 1)];
        [checkCode appendString:[NSString stringWithFormat:@"%ld", [str integerValue] * 2]];
    }
   
    NSInteger sum = 0;
    for (NSInteger i = 0; i < checkCode.length; i++) {
        //第二步： a.把在第一步中获得的乘积的各位数字相加，然
        NSInteger number = [[checkCode substringWithRange:NSMakeRange(i, 1)] integerValue];
        sum += number;
       
    }
   
    for (NSInteger i = 1; i < cardNumber.length; i+=2) {
        //b.后再与原号码中未乘2的各位数字相加；
        NSInteger number = [[cardNumber substringWithRange:NSMakeRange(i, 1)] integerValue];
        sum += number;
    }
   
    //第三步：对于第二步求和值中个位数求10的补数，如果个位数为0则该校验码为0。
    NSInteger code = 10 - (sum%10);
    NSString *fullCardNumber = [NSString stringWithFormat:@"%@%ld", cardNumber, code];
   
    NSLog(@"fullCardNumber:%@", fullCardNumber);
}

11、设置label文字属性，一半斜体一半sys，一半红色，一半黑色

    _starGoodsLabel = [[UILabel alloc] init];
    CGAffineTransform matrix =  CGAffineTransformMake(1, 0, tanf(15 * (CGFloat)M_PI / 180), 1, 0, 0);
    UIFontDescriptor *desc = [ UIFontDescriptor fontDescriptorWithName :[ UIFont systemFontOfSize :17 ]. fontName matrix :matrix];
    _starGoodsLabel.font = [ UIFont fontWithDescriptor :desc size :17];
    _starGoodsLabel.textColor = [UIColor redColor];
    NSString *string = @"/ 底价秒杀 /  人人都在抢的货";
    NSMutableAttributedString *str = [[NSMutableAttributedString alloc]initWithString:string];
    [str addAttribute:NSForegroundColorAttributeName value:RGB(68, 68, 68) range:NSMakeRange(10, string.length - 10)];
    [str addAttribute:NSFontAttributeName value:[UIFont systemFontOfSize:12] range:NSMakeRange(10, string.length - 10)];
    _starGoodsLabel.attributedText = str;
    [view addSubview:_starGoodsLabel];
    [_starGoodsLabel mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.mas_equalTo(self.contentView.mas_left).offset(10);
        make.right.mas_equalTo(self.contentView.mas_right).offset(-120);
        make.top.mas_equalTo(self.contentView.mas_top).offset(7);
        make.height.equalTo(@14);
    }];

12、截图

//截取view生成一张图片
+ (UIImage *)shotWithView:(UIView *)view{
    UIGraphicsBeginImageContext(view.bounds.size);
    [view.layer renderInContext:UIGraphicsGetCurrentContext()];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

//截取view中某个区域生成一张图片
+ (UIImage *)shotWithView:(UIView *)view scope:(CGRect)scope{
    CGImageRef imageRef = CGImageCreateWithImageInRect([self shotWithView:view].CGImage, scope);
    UIGraphicsBeginImageContext(scope.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGRect rect = CGRectMake(0, 0, scope.size.width, scope.size.height);
    CGContextTranslateCTM(context, 0, rect.size.height);//下移
    CGContextScaleCTM(context, 1.0f, -1.0f);//上翻
    CGContextDrawImage(context, rect, imageRef);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    CGImageRelease(imageRef);
    CGContextRelease(context);
    return image;
}

13、日期与时间戳互转

//将时间戳转换为NSDate类型
-(NSDate*)getDateTimeFromMilliSeconds:(long long)miliSeconds{
    
    NSTimeInterval tempMilli = miliSeconds;
    NSTimeInterval seconds = tempMilli/1000.0;//这里的.0一定要加上，不然除下来的数据会被截断导致时间不一致
    NSLog(@"传入的时间戳=%f", seconds);
    return [NSDate dateWithTimeIntervalSince1970: seconds];
}

//将NSDate类型的时间转换为时间戳,从1970/1/1开始
-(long long)getDateTimeTOMilliSeconds:(NSDate*)datetime{
    
    NSTimeInterval interval = [datetime timeIntervalSince1970];
    NSLog(@"转换的时间戳=%f", interval);
    long long totalMilliseconds = interval*1000;
    NSLog(@"totalMilliseconds=%llu", totalMilliseconds);
    return totalMilliseconds;
}

14、指纹识别返回码

a、 验证（指纹/密码）不能开启的错误信息(指纹系统被判定为无效):
LAErrorPasscodeNotSet : 设备密码未设置
LAErrorTouchIDNotAvailable : TOUCH ID不可用
LAErrorTouchIDNotEnrolled : 指纹未录入
LAErrorTouchIDLockout : TOUCH ID被锁定
LAErrorAppCancel : APP调用了- (void)invalidate方法使LAContext失效
LAErrorInvalidContext : 实例化的LAContext对象失效，再次调用evaluation...方法则会弹出此错误信息

b、 其他错误信息(指纹系统判定有效，但是验证指纹错误):
LAErrorAuthenticationFailed : 鉴定失败
LAErrorUserCancel : 用户取消
LAErrorUserFallback : 用户选择输入密码
LAErrorSystemCancel : 系统取消（如：另外一个应用进入前台）

15、解决tableView分隔线少一段的方法
在ios7中，UITableViewCell左侧会有默认15像素的空白。这时候，设置setSeparatorInset:UIEdgeInsetsZero能将空白去掉。
但是在ios8中，设置setSeparatorInset:UIEdgeInsetsZero已经不起作用了。下面是解决办法

首先在viewDidLoad方法加入以下代码：
if ([self.tableView respondsToSelector:@selector(setSeparatorInset:)]) {
    [self.tableView setSeparatorInset:UIEdgeInsetsZero];
}
然后在UITableView的代理方法中加入以下代码
- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath{
    if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
        [cell setSeparatorInset:UIEdgeInsetsZero];
    }
}