ravelantunes / cocoa-snippets

This repository is collection of code snippets that I started collecting while working on Objective-C/Swift code, so I could quick reference it.

After working a few years in various projects, I realized that I was constantly Googling or referencing older projects for pieces of code to achieve results I've done before, since I just wasn't able to remember how I've solved them previously.

Feel free to contribute with any comments or pull requests.

Objective-C Specifics

Static Properties

static NSString *myStaticString;

Random Int

Get a random int between 1 and 4:

arc4random_uniform(4)+1

NSTimeInterval to String

Transforms a time interval into a string, with 0 left padding, so 2 minutes will show as 02:00.

    //Get a time interval. This will do current time interval
    NSTimeInterval *timeInterval = [[NSDate date] timeIntervalSinceNow];

    //Get the minutes, hours, etc from the time interval
    NSInteger timeInterval = (NSInteger)self.currentTime;
    NSInteger seconds = timeInterval % 60;
    NSInteger minutes = (timeInterval / 60) % 60;
    NSInteger hours = (timeInterval  / 3600);

    //Format 00:00:00
    NSString *formatWithHours = [NSString stringWithFormat:@"%02ld:%02ld:%02ld", (long)hours, (long)minutes, (long)seconds];

    //Format 00:00
    NSString *formatWithoutHours = [NSString stringWithFormat:@"%02ld:%02ld", (long)minutes, (long)seconds];

Filtering Array

Filter array by a property of the objects:

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"id = %@", objectId];
    NSOrderedSet *results = [arrayOfObjects filteredOrderedSetUsingPredicate:predicate];

UIKit

UIButton

Set highlighted state for a button that is selected

When setting an image for the UIControlStateHighlighted state of a UIButton, that image will only be used to highlight the state for when the button is not selected. To have a highlight state for a selected button, you need to set an image for the state UIControlStateSelected | UIControlStateHighlighted (Button control state uses bitmasks).

[button setBackgroundImage:[UIImage imageNamed:@"button_image_selected"] forState:UIControlStateSelected | UIControlStateHighlighted];

UINavigationBar

Setting custom background

For portrait:

[self.navigationBar setBackgroundImage:[UIImage imageNamed:@"navigation-bar-background"] forBarMetrics:UIBarMetricsDefault];

For landscape:

[self.navigationBar setBackgroundImage:[UIImage imageNamed:@"navigation-bar-background"] forBarMetrics: UIBarMetricsCompact];

UITextField

Change placeholder font color

UITextField *textField = [UITextField alloc] init];
UIColor *color = [UIColor lightTextColor];
textField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:@"PlaceHolder Text" attributes:@{NSForegroundColorAttributeName: color}];

Or you can do this to keep the same current text that the placeholder have:

self.searchTextField.attributedPlaceholder = [[NSAttributedString alloc] initWithString:self.searchTextField.placeholder attributes:@{NSForegroundColorAttributeName: [UIColor lightTextColor]}];

UITextView

Handle return to dismiss textView, instead of adding new line

- (BOOL)textView:(UITextView *)textView shouldChangeTextInRange:(NSRange)range replacementText:(NSString *)text {
    NSRange resultRange = [text rangeOfCharacterFromSet:[NSCharacterSet newlineCharacterSet] options:NSBackwardsSearch];
    if ([text length] == 1 && resultRange.location != NSNotFound) {
        [textView resignFirstResponder];
        return NO;
    }

    return YES;
}

NSAttributedString

Defining letters spacing

The letter spacing is determined by the NSKernAttributeName attribute constant.

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] initWithString:@"My String!"];
[attributedString addAttribute:NSKernAttributeName
                         value:@(1.5)
                         range:NSMakeRange(0, 10)];

UIFont

List all fonts installed

NSArray *fontFamilies = [UIFont familyNames];

for (int i = 0; i < [fontFamilies count]; i++)
{
    NSString *fontFamily = [fontFamilies objectAtIndex:i];
    NSArray *fontNames = [UIFont fontNamesForFamilyName:[fontFamilies objectAtIndex:i]];
    NSLog (@"%@: %@", fontFamily, fontNames);
}

Add a Blur to the font's shadow

There's no way to add shadow blur through UILabel or the interface builder, so it needs to be done programatically using an attributed string. Add the following attribute to set a blur to the shadow.

   NSMutableAttributedString* attributedString = [[NSMutableAttributedString alloc] initWithString:@"Hello, shadow blur!"];
    NSRange range = NSMakeRange(0, [attributedString length]);

   NSShadow* shadow = [[NSShadow alloc] init];
    shadow.shadowColor = [UIColor colorWithWhite:0 alpha:0.2];
    shadow.shadowBlurRadius = 3.0f;
    shadow.shadowOffset = CGSizeMake(0.0f, 2.0f);
    [attributedString addAttribute:NSShadowAttributeName value:shadow range:range];

Status Bar

Controlling appearance

The way to control the appearance of the status bar depends on how you have it setup on your info.plist, with the key UIViewControllerBasedStatusBarAppearance.

UIViewControllerBasedStatusBarAppearance as TRUE

- (UIStatusBarStyle)preferredStatusBarStyle {
    return UIStatusBarStyleLightContent;
}

UIViewControllerBasedStatusBarAppearance as FALSE

[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];

It can also be animated:

[[UIApplication sharedApplication] setStatusBarHidden:NO withAnimation:UIStatusBarAnimationSlide];

UIAlertController

UIAlertController replaces the UIAlertView from previous iOS versions.

Create the controller:

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"title" message:@"message" preferredStyle:UIAlertControllerStyleActionSheet];

Add an action to the alert view:

    UIAlertAction *cancelAction = [UIAlertAction actionWithTitle:@"Cancel" style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) {
        [alertController dismissViewControllerAnimated:YES completion:NULL];
    }];

Then present it:

    [alertController addAction:cancelAction];