First
One of the features of Qur’an Memorizer, my first iOS app, is the ability to highlight a verse (ayah) when it’s tapped. To do this I access a database of verse x and y locations and retrieve the 4 coordinates I need to draw the resulting polygon.
The first version of the code released to the App Store looked a little bit like this:
- (AyahInfo *) clickedAyahForPoint:(CGPoint)point forPage:(int)page inMushaf:(int)mushaf {
int y = (int)point.y;
int x = (int)point.x;
int ayahNum = 0;
int x1, y1, y1p, x2, y2, y2p;
char * c_vloc =
"SELECT ayahNumber, x1, y1, y1p, x2, y2, y2p "
"FROM qmAyahInfo "
"WHERE mushaf=? "
" AND page=? "
" AND ( "
" (y1p < y2p AND x1 < ? AND x2 <= ? AND y1 >= ? AND y2 > ?)"
" OR "
" ( (y1p >= y2p) "
" AND "
" ( (y1 <= ? AND y1p < ? AND x1 > ?) "
" OR "
" (y2 > ? AND y2p <= ? AND x2 >= ?) "
" OR "
" (y1p >= ? AND y2p > ?) "
" ) "
" ) "
" ) ";
sqlite3_stmt * stmt;
int error = sqlite3_prepare_v2(database, c_vloc, -1, &stmt, NULL);
if (error == SQLITE_OK) {
sqlite3_bind_int(stmt, 1, mushaf);
sqlite3_bind_int(stmt, 2, page);
sqlite3_bind_int(stmt, 3, x);
sqlite3_bind_int(stmt, 4, x);
sqlite3_bind_int(stmt, 5, y);
sqlite3_bind_int(stmt, 6, y);
sqlite3_bind_int(stmt, 7, y);
sqlite3_bind_int(stmt, 8, y);
sqlite3_bind_int(stmt, 9, x);
sqlite3_bind_int(stmt, 10, y);
sqlite3_bind_int(stmt, 11, y);
sqlite3_bind_int(stmt, 12, x);
sqlite3_bind_int(stmt, 13, y);
sqlite3_bind_int(stmt, 14, y);
}
else {
// handle error
}
if (sqlite3_step(stmt) == SQLITE_ROW) {
ayahNum = sqlite3_column_int(stmt, 0);
x1 = sqlite3_column_int(stmt, 1);
y1 = sqlite3_column_int(stmt, 2);
y1p = sqlite3_column_int(stmt, 3);
x2 = sqlite3_column_int(stmt, 4);
y2 = sqlite3_column_int(stmt, 5);
y2p = sqlite3_column_int(stmt, 6);
sqlite3_finalize(stmt);
AyahInfo * ayahInfo = [[AyahInfo alloc] initWithAyahNumber:ayahNum x1:x1 y1:y1 y1p:y1p x2:x2 y2:y2 y2p:y2p]; // client should release
return ayahInfo;
}
sqlite3_finalize(stmt);
return nil;
}
Later
Some time later I learned about FMDB,
which is a wrapper around the sqlite3 C functions. This simplified my
code by adding a layer of abstraction. It was better, but still more
verbose than I would have liked,
because the methods involved need NSNumbers instead of regular
ints:
- (AyahInfo *) clickedAyahForPoint:(CGPoint)point forPage:(int)page inMushaf:(int)mushaf {
NSString * sql =
@"SELECT ayahNumber, x1, y1, y1p, x2, y2, y2p "
"FROM qmAyahInfo "
"WHERE mushaf=? "
" AND page=? "
" AND ( "
" (y1p < y2p AND x1 < ? AND x2 <= ? AND y1 >= ? AND y2 > ?)"
" OR "
" ( (y1p >= y2p) "
" AND "
" ( (y1 <= ? AND y1p < ? AND x1 > ?) "
" OR "
" (y2 > ? AND y2p <= ? AND x2 >= ?) "
" OR "
" (y1p >= ? AND y2p > ?) "
" ) "
" ) "
" ) ";
int y = (int)point.y;
int x = (int)point.x;
int ayahNum = 0;
int x1, y1, y1p, x2, y2, y2p;
FMResultSet * rs = [_db executeQuery:sql,
[NSNumber numberWithInt: mushaf],
[NSNumber numberWithInt: page],
[NSNumber numberWithInt: x],
[NSNumber numberWithInt: x],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: x],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: x],
[NSNumber numberWithInt: y],
[NSNumber numberWithInt: y]
];
if ([rs next]) {
ayahNum = [rs intForColumnIndex:0];
x1 = [rs intForColumnIndex:1];
y1 = [rs intForColumnIndex:2];
y1p = [rs intForColumnIndex:3];
x2 = [rs intForColumnIndex:4];
y2 = [rs intForColumnIndex:5];
y2p = [rs intForColumnIndex:6];
QMBVAyahInfo * ayahInfo = [[QMBVAyahInfo alloc] initWithAyahNumber:ayahNum x1:x1 y1:y1 y1p:y1p x2:x2 y2:y2 y2p:y2p];
return ayahInfo;
}
return nil;
}
Now
Now, with the introduction of Objective C literals and Boxed Expressions, it looks like this. So much nicer. Moral of the story: Take the time to learn new technologies and constructs. They could help you simplify your code greatly.
- (AyahInfo *) clickedAyahForPoint:(CGPoint)point forPage:(int)page inMushaf:(int)mushaf {
NSString * sql =
@"SELECT ayahNumber, x1, y1, y1p, x2, y2, y2p "
"FROM qmAyahInfo "
"WHERE mushaf=? "
" AND page=? "
" AND ( "
" (y1p < y2p AND x1 < ? AND x2 <= ? AND y1 >= ? AND y2 > ?)"
" OR "
" ( (y1p >= y2p) "
" AND "
" ( (y1 <= ? AND y1p < ? AND x1 > ?) "
" OR "
" (y2 > ? AND y2p <= ? AND x2 >= ?) "
" OR "
" (y1p >= ? AND y2p > ?) "
" ) "
" ) "
" ) ";
int y = (int)point.y;
int x = (int)point.x;
int ayahNum = 0;
int x1, y1, y1p, x2, y2, y2p;
FMResultSet * rs = [_db executeQuery:sql, @(mushaf), @(page),
@(x), @(x), @(y), @(y),
@(y), @(y), @(x),
@(y), @(y), @(x),
@(y), @(y)
];
if ([rs next]) {
ayahNum = [rs intForColumnIndex:0];
x1 = [rs intForColumnIndex:1];
y1 = [rs intForColumnIndex:2];
y1p = [rs intForColumnIndex:3];
x2 = [rs intForColumnIndex:4];
y2 = [rs intForColumnIndex:5];
y2p = [rs intForColumnIndex:6];
QMBVAyahInfo * ayahInfo = [[QMBVAyahInfo alloc] initWithAyahNumber:ayahNum x1:x1 y1:y1 y1p:y1p x2:x2 y2:y2 y2p:y2p];
return ayahInfo;
}
return nil;
}