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/*
     File: UIImage+ImageEffects.h
 Abstract: This is a category of UIImage that adds methods to apply blur and tint effects to an image. This is the code you’ll want to look out to find out how to use vImage to efficiently calculate a blur.
  Version: 1.0
 
 Disclaimer: IMPORTANT:  This Apple software is supplied to you by Apple
 Inc. ("Apple") in consideration of your agreement to the following
 terms, and your use, installation, modification or redistribution of
 this Apple software constitutes acceptance of these terms.  If you do
 not agree with these terms, please do not use, install, modify or

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- (void)handleTransaction:(UIButton *)sender {
    NSString *documentPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
    NSString *dbPath = [documentPath stringByAppendingPathComponent:@"test1.db"];
    FMDatabase *db = [[FMDatabase alloc]initWithPath:dbPath];
    if (![db open]) {
        return;
    }
    BOOL result = [db executeUpdate:@"create table if not exists text1 (name text,age,integer,ID integer)"];
    if (result) {
        NSLog(@"create table success");

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Use the pthread_once(_:_:) function to ensure that initialization is called before a mutex is used.

static pthread_once_t once = PTHREAD_ONCE_INIT;
static pthread_mutex_t mutex;
void init() {    
    pthread_mutex_init(&mutex, NULL);
}
void performWork() {
 pthread_once(&once, init); // Correct

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#import "NSObject+TCKVO.h"
#import <objc/runtime.h>

@implementation NSObject (TCKVO)

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        [self switchMethod];
    });

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#import <objc/runtime.h>

@implementation UIViewController (Swizzling)
+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];
        // When swizzling a class method, use the following:
        // Class class = object_getClass((id)self);
        SEL originalSelector = @selector(viewWillAppear:);

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@implementation UIViewController (AlertObject)

- (UIViewController *)visibleViewControllerIfExist {
    
    if (self.presentedViewController) {
        return [self.presentedViewController visibleViewControllerIfExist];
    }
    
    if ([self isKindOfClass:[UINavigationController class]]) {
        return [((UINavigationController *)self).topViewController visibleViewControllerIfExist];