Adding Days to an NSDate

iPhone SDK Tips & Tricks

NSDate *now = [NSDate date];

int daysToAdd = 50;

// set up date components

NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];

[components setDay:daysToAdd];

// create a calendar

NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];

NSDate *newDate2 = [gregorian dateByAddingComponents:components toDate:now options:0];

NSLog(@"Clean: %@", newDate2);

Try Catch

iPhone SDK Tips & Tricks

@try {

[self doSomethingFancy];

}

@catch (NSException* ex) {

NSLog(@"doSomethingFancy failed: %@",ex);

}

Delete a File in Documents Directory

iPhone SDK Tips & Tricks

To access the secondary directory in the documents directory:

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentsDirectoryPath = [paths objectAtIndex:0];

NSString *secondaryDirectoryPath = [documentsDirectoryPath stringByAppendingPathComponent:@"secondary"];

NSString *databaseFile = [secondaryDirectoryPath stringByAppendingPathComponent:@"database.db"];

NSFileManager *fileManager = [NSFileManager defaultManager];

[fileManager removeItemAtPath:databaseFile error:NULL];

Get the Amount of Free Memory Available

iPhone SDK Tips & Tricks

#import <mach/mach.h>

#import <mach/mach_host.h>

+(natural_t) get_free_memory {

mach_port_t host_port;

mach_msg_type_number_t host_size;

vm_size_t pagesize;

host_port = mach_host_self();

host_size = sizeof(vm_statistics_data_t) / sizeof(integer_t);

host_page_size(host_port, &pagesize);

vm_statistics_data_t vm_stat;

if (host_statistics(host_port, HOST_VM_INFO, (host_info_t)&vm_stat, &host_size) != KERN_SUCCESS) {

NSLog(@"Failed to fetch vm statistics");

return 0;

}

/* Stats in bytes */

natural_t mem_free = vm_stat.free_count * pagesize;

return mem_free;

}

NSLog(@"free memory: %d", [self get_free_memory]);