分享一些iOS开发实用的小技巧

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

 UIColor *color = [UIColor colorWithRed:0.0 green:0.0 blue:1.0 alpha:1.0];const CGFloat *components = CGColorGetComponents(color.CGColor);NSLog(@"Red: %f", components[0]);NSLog(@"Green: %f", components[1]);NSLog(@"Blue: %f", components[2]);NSLog(@"Alpha: %f", components[3]);

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

 - (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;}

/** * 获取按钮title的size */- (CGFloat)getBtnTitleWidth:(UIButton*)btn { CGSize titleSize = [btn.titleLabel.text sizeWithAttributes:@{NSFontAttributeName:btn.titleLabel.font}]; return titleSize;}

UIView *view = [[UIView alloc] initWithFrame:CGRectMake(0, -20, ScreenWidth, 20)];[view setBackgroundColor:COLOR_APP_MAIN];[viewController.navigationController.navigationBar addSubview:view];

+ (NSString*)dictionaryToJson:(NSDictionary *)dic { NSError *parseError = nil; NSData *jsonData = [NSJSONSerialization dataWithJSONObject:dic options:NSJSONWritingPrettyPrinted error:&parseError]; return [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];}

+(NSDictionary *)jsonToDic:(NSString*)jsonStr {  NSData *jsonData = [jsonStr dataUsingEncoding:NSUTF8StringEncoding];  NSError *err;  NSDictionary *dic = [NSJSONSerialization JSONObjectWithData:jsonData               options:NSJSONReadingMutableContainers                error:&err];  return dic;}

+(BOOL)isAllowedNotification{ if ([[UIDevice currentDevice].systemVersion floatValue] >= 8.0) {  UIUserNotificationSettings *setting = [[UIApplication sharedApplication] currentUserNotificationSettings];  if(UIUserNotificationTypeNone != setting.types) {   return YES;  } } NSLog(@"不允许推送"); return NO;}

+ (NSString *)memoryFormatter:(long long)diskSpace { NSString *formatted; double bytes = 1.0 * diskSpace; double megabytes = bytes / MB; double gigabytes = bytes / GB; if (gigabytes >= 1.0)  formatted = [NSString stringWithFormat:@"%.2f GB", gigabytes]; else if (megabytes >= 1.0)  formatted = [NSString stringWithFormat:@"%.2f MB", megabytes]; else  formatted = [NSString stringWithFormat:@"%.2f bytes", bytes]; NSLog(@"fotmatted=%@",formatted); return formatted;}+ (NSString *)totalDiskSpace { long long space = [[[[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:nil] objectForKey:NSFileSystemSize] longLongValue]; return [self memoryFormatter:space];}+ (NSString *)freeDiskSpace { long long freeSpace = [[[[NSFileManager defaultManager] attributesOfFileSystemForPath:NSHomeDirectory() error:nil] objectForKey:NSFileSystemFreeSize] longLongValue]; return [self memoryFormatter:freeSpace];}

 //设置代理self.interactivePopGestureRecognizer.delegate = self;#pragma mark - <UIGestureRecognizerDelegate>//实现代理方法:return YES :手势有效, NO :手势无效- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{ //当导航控制器的子控制器个数 大于1 手势才有效 return self.childViewControllers.count > 1;}

/** 设置圆形图片(放到分类中使用) */- (UIImage *)cutCircleImage { UIGraphicsBeginImageContextWithOptions(self.size, NO, 0.0); // 获取上下文 CGContextRef ctr = UIGraphicsGetCurrentContext(); // 设置圆形 CGRect rect = CGRectMake(0, 0, self.size.width, self.size.height); CGContextAddEllipseInRect(ctr, rect); // 裁剪 CGContextClip(ctr); // 将图片画上去 [self drawInRect:rect]; UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return image;}

//xib的awakeFromNib方法中设置UIViewAutoresizingNone进行清空 - (void)awakeFromNib { self.autoresizingMask = UIViewAutoresizingNone;}

- (NSString *)contentTypeForImageData:(NSData *)data { uint8_t c; [data getBytes:&c length:1]; switch (c) {  case 0xFF:   return @"jpeg";  case 0x89:   return @"png";    case 0x47:   return @"gif";    case 0x49:   case 0x4D:   return @"tiff";    case 0x52:    if ([data length] < 12) {    return nil;   }   NSString *testString = [[NSString alloc] initWithData:[data subdataWithRange:NSMakeRange(0, 12)] encoding:NSASCIIStringEncoding];   if ([testString hasPrefix:@"RIFF"] && [testString hasSuffix:@"WEBP"]) {    return @"webp";   }   return nil; } return nil;}

NSInteger count = 5;//02代表:如果count不足2位 用0在最前面补全(2代表总输出的个数)NSString *string = [NSString stringWithFormat:@"%02zd",count];//输出结果是: 05NSLog(@"%@", string);